To be honest, I don't understand what the hell was wrong with trap. Short, old enough a meme for everyone to know, easy to remember.
Offensive? Really? Did anyone actually complain about it? If it was a preemptive strike, so to say, you'll soon need to tag any passive gay character as 1girl, because "he identifies that way", and it's offensive to keep calling him "boy". (/sarcasm)
Anyway, if you don't like trap that much, why not male_crossdresser and female_crossdresser for reverse_trap then?