The lights are running off the camper's 12V system. Just jumper pins 3 & 4 of the TV power cord. This connects the camper's 12 pin to the tail light pin.
Make sure you use wire large enough to carry the load.
I just saw where someone suggests using a 5 amp blade fuse. Just plug the fuse into sockets 3 & 4 on the campers TV plug.