Maybe you can try to put yourself in my place, try to imagine how you would feel if you were the parent and your precious kid was about to get all dressed up and go out into the world at night and stay out really late. Set a curfew. Your child might be angry, but oh, well. You be one who does. The kids with curfews outnumbered those without, and I sense the kids with curfews seemed a little bit proud.
Some adults rent motel rooms for minors on prom or graduation nights.
If you're fresh out of horror stories about groups of teens in motel rooms, borrow a story from Roosevelt, a school in St. Johns with 1,100 students. There was the female student who got drunk, stripped, danced and personally obliged several males. It took several days of mediations to get through the scandal, and she did not emerge unscathed. Almost every year at Roosevelt, the Monday after the prom brings fallout from some scandal that happened before or after the dance in an unsupervised setting, always involving safety issues and reputations. Someone in your stead As a parent, you can offer your home for the gathering or insist on a supervised setting.