The only solution to the bathroom debacle is kindness. If you see someone in your preferred bathroom who makes you feel uncomfortable because they are different than you, smile and do your business. Or smile and say, are you almost finished? Or smile and leave. That person's life is difficult enough without your making it more difficult.
And if a young woman or man comes into the bathroom and is clearly made uncomfortable by your presence, smile and say, "I'm almost done." The young person has no experience, probably has no context, and a little kindness will go a long way toward reducing anxiety. Just because you think they are wrong doesn't mean you can't treat them kindly.
And if anyone, of any gender, in any bathroom, is misusing the bathroom for bullying, or for abuse, or for peeping or leering or invading privacy or whatever, then we all need to band together to get that person to knock it off (with law enforcement if necessary), because we all should feel safe in bathrooms.
(And if you are an adult and see a transgender person using the bathroom for what it is for, then you should get on with your business even if you are uncomfortable. Because we are adults and disagreeing with someone is no excuse for hurting them. Get a life.)
Unfortunately, it seems that we are a long way past kindness in this country.