They should have a bathroom. It should be their born sex.
If not, then fine, put in a third bathroom.
There’s no reason normal women should have to stand shoulder to shoulder with men.
I personally do not want women in a bathroom with me. I don’t want men in my wife’s bathroom.
It should be the plumbing at the time you unzip. If you mutilated yourself and you no longer have parts then go in the other if not go with how you were born.