Mexican Navy working uniform question

Hello everybody. I saw the great drawing Sean did on the Mexican Navy's WWII-era square rig uniform and was wondering if anybody has any information on what Mexican Navy enlisted ratings wore as a working/fatigue uniform? It is quite hard to find pictures online of Mexican Navy ships and personnel from that era and the best I could find were a couple websites, this one and an old Mexican postcard site which had a few featuring Navy themes from (I'm guessing) the early 1900s to 1920 era. This one here has probably the best (and it's not good) photo of what I'm presuming to be Mexican Navy working uniforms as they are going about their sailor business rather than standing at attention at the rail.

http://www.histarmar.com.ar/ArmadasExtranjeras/Mexico/UnaArmadapMex.htm

It's the one of the coastal patrol craft class called "Guardacostas Tipo 20" about halfway down the page. Now it isn't a very big photo and doesn't have a good clarity but to me it looks like the ratings are wearing a "dixie cup" style cap but dyed navy blue and (maybe) a navy blue jumper and trousers. Maybe the Mexican Navy (not among the world's most lavishly funded, and no offence meant to Mexico at all) might have used as its rating's working uniform just a second set of his same basic uniform used with the square rig, just minus the blue jean collar and cravat (and with a navy blue-dyed cap instead of white)? I have seen some other navies of the era appearing to be doing something similar as opposed to (or perhaps in addition to) having a separate fatigue working rig uniform. What are you fellows' thoughts on it?

Though the fourth sailor from the stern looks like he MIGHT possibly be wearing a lighter (than navy blue) coloured jumper and trousers, perhaps gray as was popular in some navies of the era? Or it could simply be a lighting trick in the photo and not a different uniform as the other sailors.

Update: In looking through the resource material on the Mexican Navy's website I may have a possible answer. It was a story about a Mexican tanker that was apparently torpedoed by a German U-boat and it had a few photos. One was a rating wearing what looked like a traditionally-cut (gray?) working jumper with same material neck flap but with two thin white stripes along its edge. Unfortunately it was only a portrait-style photo so I could only see a small bit of it but it was definitely way lighter in colour than if it was navy-blue so I'm guessing maybe a medium gray? This was a popular working rig uniform colour in a lot of navies of the era. Also unfortunately he wasn't wearing his cap so I can only guess but would assume it would be the same (sort of U.S. Navy-style) sailor's cap in white like with the square rig uniform or maybe dyed navy blue. None of this would preclude the possibility of Mexico's navy also using a different working uniform in addition to it though.

...here is what little I have anyway:

Naval Uniforms
All navies of the period wore similar uniforms following that of the British Royal Navy and standardised on the basic colour of all items being dark blue, with white summer/tropical alternatives. The uniforms worn by the Mexican navy showed a strong United States influence.

Officers
The 1912 regulations were replaced in 1920 with few changes.  There were four orders of dress for officers: Number 1 Gala, No 2 Ceremonial, Number 3 Special Service and Number 4, Regular Service.

Uniform Number 1 Gala, was frockcoat, waistcoat, trousers with belt, black patent leather shoes, cocked hat, epaulettes, embroidered belt, white gloves and decorations (medals). This was used on national holidays, to receive on board ships or units of the Navy the President of the Republic or heads of state of friendly nations and ceremonies, meals, dances and receptions. The frock was dark blue cloth with insignia of rank on the sleeves.

Number 2 Ceremonial Dress was dark blue cloth and consisted of coat with rank insignia on the sleeves, waistcoat, trousers without belt, black patent leather shoes, cocked hat, epaulettes, embroidered belt, black tie, white gloves and decorations. It used to receive official visits of the Secretary of the Department, ministers or representatives of friendly nations and members of royal families; for visits to foreign warships; to attend funerals and when determined by the Commander.

Uniform Number 3, Special Service, was dark blue cloth coat with transverse shoulder bars that showed rank insignia, waistcoat, trousers without belt, black shoes, hat, belt without embroidery, tie, gloves and decorations. It was to be used to receive or visit in their official capacity secretaries of state, state governors, generals and commanders Division Chief Fleet, Division or Department; for dances, dinners, official gatherings and other acts of society in which so decided Commander; to mount guards in a foreign port holidays; training stops and other acts of service that is ordered by the Commander. In summer and warm climates, the special service uniform was modified with white cap and trousers.

Number 4 Regular Service uniform was for winter and summer. In the winter, dark blue jacket and trousers, black shoes, white cap, belt without embroidery, dark gloves and medal ribbons (decorations).
The regular summer service uniform was similar for all departments of the Navy, of white jacket, white trousers, white shoes, white cap, belt without embroidery, white gloves and decoration ribbons.

Swords were similar to British RN pattern but with the lion’s head pommel replaced by a condor’s head and with a condor and anchor in the cartouche. Blade slightly curved, with gilt hilt and ivory grip; black leather scabbard with gilt mounts; worn on a black leather or silk waistbelt, which was often embroidered, over the coat. Warrant officer’s sword similar but with plain pommel and backpiece.  

Epaulettes: Gold epaulettes with fairly thick bullions were worn by all ranks and had two crossed silver anchors on the crescent for flag officers; foul anchor for senior officers, plain crescents for junior officers.
Officers' Caps: Dark blue flat-topped caps with black patent leather peak and chinstrap; black silk or mohair band, on the front an anchor or the national cockade in a laurel wreath with crown or national badge above. This cap was also worn by warrant officers, but without the wreath. The upper part was broad or close-fitting, according to fashion.

Frock Coat: Long-skirted, with two rows varying between three and six buttons, which usually bore an anchor device. It was worn open at the top, like a civilian coat. At the back were skirt pocket flaps, with two or three buttons. Gold lace stripes, according to rank, were worn on the cuffs.

Jacket: Double-breasted, cut like the frock coat, but with skirts varying in length between medium and short. No buttons at back; rank lace worn only on the sleeves. It was also worn by warrant officers and chief petty officers. Warrant officers wore one to three narrow stripes around the cuffs; petty officers had narrow gold chevrons, point up on the upper arm, with the branch badge below. In the white summer/hot climes uniform instead of their normal frock coats or jackets, officers wore a single-breasted tunic  

Sailors

Sailor’s Cap: Dark blue; white for summer, with flat top and narrow band, peakless. The base was surrounded by a black silk ribbon or tally, on which was printed, in gold or yellow lettering, the name of ship. The ends of this silk band hung down, or were tied in a small bow on the left or right side.

A photograph of sailors on board the Yucatan are wearing Sennet-type straw hats; the brims are worn up and the edge is bound with a narrow dark (blue or black?) trim.

Jumper: dark blue; white in summer; broad collar hanging down at the back and forming a deep vee on the chest, jumper usually worn tucked into the trousers like a shirt but also worn outside. With it was worn a light- or medium-blue collar, hanging down over the shoulders at the back, with three narrow white stripes around the edge (the illustration with 1930 Regulations shows a single small white star in the two corners). Under the collar was a black silk tie, worn in a knot on the chest.  

Shirt (Undershirt): white with a blue edging, and only visible at the neck of the jumper.

Pea Jacket: Short double-breasted coat reaching to the hips, with a flat turndown collar, open in front, with broad lapels. With this jacket, the jumper collar was worn underneath.

Trousers: Dark blue, closed with a flap in front. The legs were traditionally bellbottomed, and almost covered the shoes.

White Clothing: In summer, and in the tropics, almost all items of dress were duplicated by similar ones made of white linen.  In the photograph of sailors on board the Yucatan, they are wearing the blue jumper and collar with white undershirt, trousers and shoes.

Nothing on a working dress, sorry. I suspect that the financial situation of the navy during the Revolution would mean old blues and whites had to serve?