Stealth X-Wing Flight Suit (comic) and some other flight helmet/equipment det...
You have to step back and consider what SW universe deigns really are. Remember, Star Wars is Fantasy, not sci-fi. The look of ships, costumes, props are not designed from a reality standpoint but to make a certain visual imapact to the audience. A lot of ST ships, props and designs just don't make sense but as fans of this fantasy world, we accept them. The X-Wing pilot costume itself has a lot of real world design flaws (don't get me started) but we like it for what it is and what it represents.
As a Naval Officer, with over 20 years of Naval Aviation experience, I can tell you that the standard nomex green flight suits come in female cuts. So why not in the SW galaxy?
Also, if you want to put some sort of justification behind it. What really is standard for pilot in a rag-tag rebellion. Do certain ships have certain outfits? I say no. Look at Y-Wing pilots in ANH compared to ROTJ. I argue that the rebellion would have to make do with whatever items they can get their hands on. If you had 12 X-wings, 12 pilots, and 11 orange suits and 1 purple suit, do you only send out 11 ships and wait till you get another orange suit? I think not.
Still would go with the gray vest and embrace the images of the ones that show it. Why should you want to look like a flying milkman? The standard issue white vest as an excuse doesn't hold up because she is wearing white flight suit. How is that standard? Is that white flight suit specially made? Then why not a gray flak vest? Is that white flight suit one of many (we just have not seen the many others who wear one)? Then why not the gray flak vest. See where I am going with this?
IMHO... if I were doing a custom pilot costume, I would want it stand out, not just color swaps... and I would want to look AWESOME in it. I would want women to want me and men to want to be me