Oftentimes, as long as the room passes whatever end-of-year-check-out-inspection-thing they have, people really don't care. (And, hey, if people complain, you can always say "I found the glue residue unsightly and wanted to cover it up, and look, my stuff comes off without a mark." That's another thing to keep in mind; most if not all of the people you'll be dealing with are human, and are willing to flex. Even in a gigantic organization like a university. All the rules are intimidating, but most people will work with you to make everythign run smoothly and pleasantly.)