I belong to two Martial Arts schools in Chicago and both have been really cool about me being trans. Not specifically MMA, but I do a mixed art at one place and BJJ at the other. Anyway, I dislike many of the things you mentioned about the more public MMA issues. They are behind the times as far as tolerence and could use some research. And Rousey's bad sportsmanship pisses me off, period. I don't know of any sites that have been cool, but I have competed in BJJ under an association that was very open to discussing me transitioning, and competing as a Male in a few years. So, if you want info on them, or are interested in whatever, you can message me. I don't want to be too open about where I am in a public forum.
-Bear