My solution to this was to add a DPDT on/off/on switch. With the intent of being able to power it from the 12V power station as originally installed or from the clearance lights but also be able to completely turn it off if desired. There is a clearance light about 18” or so straight above the install location. Access to the clearance light wiring was easiest from the outside so pulled the light loose and used a couple of through the insulation splice connecters to tap into the lines. This all fit back through the hole in the front cap and the wires were easy to fish down the wall.
This picture is a bit blurry but shows the splice connectors at the clearance light.
There was plenty of wire included with the original install so I was able to cut the red and black power wires coming from the original 12V power source and put the crimp connectors on for the switch. Here is the switch all hooked up.
I enlarged the wall opening to make access easier and provide enough space to mount the switch and transmitter to the plastic wall plate. The transmitter still had the cover on the adhesive so I was able to stick to the back of the wall plate which will ensure it is pointing in the correct orientation to maximize the signal at the tow vehicle.
With it all cleaned up and the wall plate in place you can just barely see the black switch on the black plate.
I haven’t gotten a chance to check the operation from the tow vehicle yet but I was able to see the camera come on when the switch was in the 12V supply position and go off when switched to the off position.
Parts I used:
1 – JR Products 13345 Black DPDT Mini on/off/on switch (amazon $7.36)
6 – 3M Disconnect Terminals 22-18 AWG female (package of 25 for $8.70 at local electrical supply store) (was only rated down to 18AWG but worked fine with the 14 gauge stranded wire I already had)
2 – 14 gauge stranded wires about 3 feet long (2 pieces I had from a different project)
6 – 1” long pieces of heat shrink (used to reinforce wire going into disconnect terminals at switch)