I had the same problem with my 2021 GMC Sierra 3500, and fixed it by adding a Buck/Boost module to the camera power. The truck was only putting out 12 volts for the running lights at the socket, and after running through 50 feet of wire in the trailer it was only about 11.4V at the camera. The Buck/Boost module solved the problem. Bought it from Amazon: Amazon.com
I also added a single pole, double throw switch to the running lights to they can be powered either by the truck or the RV battery.
I also added a single pole, double throw switch to the running lights to they can be powered either by the truck or the RV battery.