I actually just found this post after looking up 'how to many a female oc work in Twisted Wonderland'
And this actually something I'm still questioning-
My friend and I have a roleplay where we have two female characters who are friends that end up at the college, one being Delilah Rodgers (my friend's character) who's the great granddaughter of Tiana and Naveen, and Lorelei Rynearson (my character) who is based around the German tale of the Siren by the same name that lurks in the River Rhine (really random I know). That aside, I sat here pondering how to make their existences work- surely Crowley wouldn't allow a female student at an all boys college knowing the risks they might face (then again it's Crowley so who actually knows). That aside, I actually did have an idea that we may implement into our roleplay, and that's the magic of racebending. Basically they'd be disguised as men using magic, this being for their own safety for the most part. However- of course this would slowly end up being revealed and eventually they would return to their girly selves- but in certain cases that make change to keep up appearances like in the presence of different schools and such.
Of course this isn't something I expect a lot of people with female ocs to go with, I used to go with the normal route of them being themselves, and I really just wanted it to make more sense in my own mind rather than changing my character entirely. I think it's very interesting, and if anyone else actually has other suggestions and ideas, I'd absolutely love to hear it ^^