I didn't want to drill into the bumper on mine so I used Industrial Strength Velcro strips. Those backup lights held on for four years without ever coming off. The best part of using the industrial Velcro was that I could reposition them whenever I wanted. I just wish I had taken a picture of it.
I then ran the supply wire to a blue LED rocker switch just inside the door and tied it to the trailer's battery instead of relying on the TV. I did use them a time or two when not hitched up to the TV so it was a useful way to do it.