Ideas to address truck tail light reflection from camper?

All the lights in the rear have to have a ground. You could add a relay that the lights ground through. I'd wire it up so that when I applied power to the new relay (using a switch on the dash) it interrupted the ground path for the taillights. It would require a 5 terminal relay and some wire and time. You could kill as many lights as you wanted to by removing their ground path.