Coming back to this specifically, because it was a decent question, politely framed.
For me, it's all about balancing different needs. It's pretty obvious that there isn't a ' perfect ' solution ie one that makes everyone happy. If there was, someone would have found it by now.
So we have to find the compromise that is most practical, most workable, satisfies the needs of the most people.
I've already said I think we should trans-specific prisons, and rape support groups that are either specifically trans-inclusive, or trans-exclusive. That way everyone is safe.
I've also already said that I think trans women should not be competing in women's elite sport.
Regarding bathrooms and changing rooms however, it's more complicated. Mixed facilities are fine - but difficult to retrofit where they don't already exist. But ultimately, I believe that the right of trans women to have a space to shower / pee / get changed is greater than the right of non-trans women to be protected from the occasional sight of a penis.
If the trans woman in those facilities is intimidating, masturbating, leering, or whatever - then call an attendant, or better still, a cop. Just like you would if it was anyone else behaving in a threatening way.
But if all they're doing is having a shower and getting dressed, then what's the damn problem?