Are you saying that men cross dress in large numbers to become sexually aroused?
Yes, I am. I am absolutely astonished that this paraphillia seems to be news to you. It does explain how dismissive you are of women's concerns though.
I guess it's possible but if that's why they're doing it I'm not sure they'd regard themselves as being under the transgender umbrella. I think you can differentiate them from folks with gender incongruence, lifelong or otherwise.
According to Stonewall they come under the transgender umbrella. If you are going down the 'You are who you say you are' view, these men with fetishes have as much right to say they are women - and have the access you seem happy to give away - as any other man.
Why wouldn't they regard themselves as transgender? It gives them access to women's spaces, legitimises their paraphillia, and it gets men like you to advocate their cause. There's nothing to lose.
How? How do we differentiate them when they are demanding access to women's spaces and services?
Research. This study says 2.8% of men, and 0.4% of women. Which would equate to 600,000 men over 18 in the UK.
https://pubmed.ncbi.nlm.nih.gov/15859369/
I don't believe for a minute though that you are unaware that there are men for whom dressing as a woman and being in women's spaces is a huge sexual thrill.
It's just another way to other TW and cast them as both sexually perverted and a threat.
No, it's an acknowledgement that there is no way of telling the difference. Perhaps you can explain how we can tell in a vulnerable space.