Do they ban all Boiga or just B. dendrophila? If only dendrophila, then I would recommend cynadon. If you want something a bit of a step up, get Boiga blandingii, this is an African species and easily the largest of all the Boigas.
Another good snake, although not a rear fang per se but is a real handful, is Ptyas carinatus (ridge back ratsnake). Looks like a king cobra, gets four meters, totally mental but absolutely stunning.