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

Bka0721 had a very sensible and logical explaination about this topic. Paraphrasing Bryan, "if you have tail lights on the back of your camper for people to see, a license plate should be there too". I move mine every time from the truck bumper to the bracket on my camper. In Ca, that is the plate with registration month and year tags are adhered to. We also have 2 plates issued and both must be in place.