I've been volunteering at the library on my daughter's campus. Last month I showed up one day with a femme top: blouse, jacket, necklace, etc (but slacks & dude shoes).
Next week I asked a trusted librarian if it was OK (I figured it was supposed to be a "safe zone"), and also thought I'd ask the admin to talk with us - if I was to do this, I wanted to go through proper channels. So the admin got the process started to allow me to do this.
Next week the supervisor wanted to talk to me - amazingly she was very supportive. We also talked with the person on campus who handles LGBT issues, and there have been meetings and emails to let workers know there will be a TG volunteering at the library.
So today the supervisor said, when I come in Thursday, I can dress in what I'd like (within professional dress code, of course) .