Good Morning ("morning" at lest here) to you all...
Man, I think you´ve hit the pot.
More or less I had a similar idea: after watching one of the espisodes of my favourite ANIME series (COWBOY BEBOP), one in wich Spike or somebody (I can´t remember well who was) were "fighting" in some planet of the Sol System, I saw them firing good ol´( ;D ) H&KG36 in a planetary desertic environment.
... Then I had the "idea" more or less of what you´ve suggested: I thought that it could be feasible / cool to take either a Chally-2 or a Leo 2E6 (those two AFVs along with any T-80 covered with reactive armour are the ones that I like more for those purposes) and paint it "Martian Red", weaterizing it accordingly to the environment...
The same more or less for any modern troops figures: colors accordingly to camo schemes of imaginary "distant" planets.
Well, that was a more or less "similar" idea to the one you´ve launched, I think.
In modelling, comparing the balance between "strict fidelity to historical reality" and "artistic / imaginative modelling"... I think I´m more or less on a 40 / 60, favouring the second "style"...
I think that the possibilities are almos endless... and this is a HOBBY just to enjoy (at least for me ;D )
Cheers, guys
RG