Do men waves their genitals at you a lot in changing rooms Dan?Wave your willy 5 times at Matlock.
Tell her you go by Mary in the Sports Forum and your Johnson will simply become invisible to her.
Because in my 40 plus years of going into changing rooms I have yet to encounter anyone waving their genitals around the place.
Why is it that you think trans people (who are far far more likely statistically to be assaulted than to assault anyone) would want to wave their genitals around a changing room?