I think the best way to handle this would be to get a bunch of parents together and talk to the principal and the athletics director together. Heck, bring in the ethics code of conduct. I know you said the other parents might be worried about worse treatment for their daughters, but really, if it gets worse, keep going back until this man is forced to change his behavior or leave. Heck, if there's a school counselor or therapist, get them involved too. The other parents might be thinking the same thing, that they couldn't get anyone to go with them. It doesn't hurt to start asking. Good luck!