Locking trailer hitch pin? Bike lock...and the previous owner forgot to take the key? I think keeping the unknown keys in a drawer in the RV would be a wise idea, at least for awhile, lest you discover something they went to at an inopportune time and not have them handy.
I "only" have five keys for my RV: a Ford key for the ignition and front doors, a round and a square key for the main entrance door latch lock and deadbolt, a CH751 for all the storage compartments, and a little emergency key for the cheap electronic safe I installed to keep s'mores chocolate safe from those who might otherwise be overcome by temptation (and also handy for petty cash and passports and such like things).