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.