I know you didn’t mention eunuchs, the OP did. You mentioned Marines, and I equated “girls posing as boys” with cross-dressers.
Maybe that was wrong – I don’t know enough of the subtlties of psychology to say if the terms are equivalents.
Damn, I’m trying and failing to come up with some witticism regarding Marines, eunuchs and cross-dressers. You’d think something like that would practically write itself.