Hohoho, without moving the primary purpose away from finding someone who could imagine these, this requires some curious thought.
A lot of the United States Navy traditions (incl. uniform) are derived from UK Royal Navy traditions, which then come from centuries worth of some really archaic and anachronistic practices, yet have just stuck. The default idea of "Men in manly stuff, women in feminine stuff" for Gallente, for example, would be our automatic assumption, because we might see the Fed military as your standard, Terran volunteer military that has taken American values into space (eg. Star Trek).
But as Matariki points out, what's stopping the Gallente from having skirts for men? My initial reaction to her post was "No, that's gaaaaaay and stoooopid" (though I would say that the women, if they did wear skirts on a spaceship rather than a ubiquitous jumpsuit, would wear fire-retardant tights), but that's just me projecting my RL values onto it. There's the question if the Fed military traditions are standardized between all major members for political equality reasons, or if it's just those wacky Gallente shoehorning their traditions in. Even then, Gallente never had a Christendom like US/Europe does, and with the major landmark in Caille being a cathedral to some goddess, one can really have no idea*.
Then there's the question if one sees the Caldari as a "Gallente offshoot", that their military retains trappings of the Federal one, and never really updated it because of "it ain't broke, don't fix it". The Amarr I'd definitely see as having some traits that were adopted for reasons dating back hundreds of years. One could assume the Republic Fleet retain their Gallente structure and foundation (again changing the fundamental structure for vanity reasons might be a bad idea and impractical), but aesthetically and other matters, have been adding in their tribal stuff.
BUT, rather than turning this into another chin-wagging thread, best to just go with one set idea for whoever steps up.
*I believe in the Gallente religion article it says the ethnic Gallente have strong definitions of masculinity and femininity. How this manifests itself is any one's guess.