I have said for awhile now, the solution is to simply label them penis and vagina. No mater what you “identify” as, you have to have THOSE parts to use that area.
So if some mentally ill man has had his penis removed and now has a vagina.. then welcome in!
otherwise use the room market penis! because no one in the vagina area wants to see you penis.
I’d go with XX or XY. XXY can pick.
I wouldn’t want she/he in the Men’s locker room either.