A boy who strongly wants to dress as a girl, but for any or all of many reasons has not, is he a crossdresser? The dictionary says no.
A man who never had that internal drive to wear women's clothing but did for costuming/theatrical reasons, is he a crossdresser? The dictionary says yes.
A crossdresser who is not attracted to and was never intimate with other men, but is attracted to or excited by the idea (fantasy) of being with a nameless, faceless man when dressed, is he gay?
Some might say "leaning gay" but how about "straight so far"?