I installed a Voyager camera in the back of my 2006 Bambi, mounted on the license plate frame. I just tapped into the license plate cables (going to the bulb), and ran my Voyager off of that. I don't know if this works for you. Yes, you must have the lights on- but I consider it a great safety reminder. It rocks. It is so great to see what's behind you, things that extended mirrors simply miss.
I did it by ordering a couple adapters that prevented me from having to cut any wires. I got a 2:1 tail light splitter that made the single bulb socket into two. I put the bulb back into one of the sockets (actually, I put in a bright LED bulb instead, but that is irrelevant). Then I plugged in a Bulb-socket-to-2-wire assembly that brought the two wires out for 12V
power. I spliced these into the assembly Voyager give you for power. If you bring in your taillight bulb into a NAPA or other dealer, you should be able to get all these parts. I ordered on Amazon. That's it. Voyager has great range. I powered it up and drove around the block, and you had to be a half block away to lose signal.
I put the quick disconnect loosely behind our license place. I used a knurled knob to attach the Voyager. If I choose, I can disconnect the rear view camera in a minute, and put it away for anti-theft.
Don't know if this works for you or not.