License plate on Truck? or camper (with overhang)?

The first time we took the Lance out I put the plate on the camper. We drove down to the park and unloaded the camper. The next day we drove an hour over to a Bass Pro shop. Once there, we got out of the truck and realized the plate was still on the camper back at the park.:S
We don't unload the camper very often but if we do the first thing I do is switch the plate back to the truck.