The school can have rules about guns on campus. Thus, the police may not arrest you in a situation as described, but if you are a student - you can be thrown out, suspended or the like.
Employees can have guns in their cars.
I would strongly advise against having an identifiable gun indicator like printing. You may be legal but you might eat dirt. You can complain later.
Please do not mention that you will break a law or a school rule on this forum.