this probably wont happen due to health and safety
mainly safety for the other students who aren't playing, you will need to get allot of netting around the Field, strict refs who make sure everything is safe before you go out of the playing area, and some way to make sure other people wont be dumb c*nts and shoot people who are not wearing a mask/ proper safety equipment around the school.
because of that your best option is to look for the closest paintball site and try and arrange the tournament to be held there, then all you will need to do is to get the school to take you there, bring you back and to get teams together