G'day stalintc,
I've actually been working on that to be part of a new periscope/UI mod I'm working on. Still haven't quite got it to do what I want it to, but I've got the screen filtres finished.
My plan is to have a button on the periscope/s screen/s to turn on or off up to two different colour filters. Don't know yet if this can be done, but is on list of hings to do/try.
Report on U-570 http://www.uboatarchive.net/U-570BritishReport.htm
Colour Glasses
19. Two colour glasses are provided which can be introduced singly or together near the focal plane of the eyepiece. One of the glasses is a bright orange and the other a very deep neutral. The neutral glass had the appearance of being a lightly metallisied glass.
TheDarkWraith

and Reaper7

have given me a little help because I'm a complete numpty with code/script.
My periscope UI will be based on SH3 style, with some "tweeking" the idea will be to have a UI thats a little less star trek and a little more period (emersive).
Happy Snaps:
Based on photos of U-boat parts
and of course coloured filters for the periscope views
Unfortunately tis slow progress (did I mention the code/script numptiness?

)
Its not even worth starting a WIP thread because this UI work seems to take forever.