This fuss about trans women using the ladies is getting out of hand (deliberate pun). Let's face it, the number one reason that there are separate toilets for the two main genders is because men have the rather disgusting habit of peeing on the toilet seat.
Therefore, rather than getting their knickers in a twist (another deliberate pun), legislators should bring in a universal law that everybody should go to the loo sitting down. Then we could have unisex restrooms (without urinals) without women, of either physical gender, having to sit in piss.
End of problem.