Disclaimer - the rear view camera on our Greyhawk can be left on, so this is a guess.
When I installed a wireless Bup camera on our old motorhome, they all seemed to have similar power connectors. If it were me, I'd probably grab just the cable/cord off eBay for a few bucks. ( Assuming the camera can be aimed up. Some are just set in plastic and cannot. )
Then I'd try to figure out how to run the wire from some 12V source to the camera.
Or - you can say "#$%^ it, and buy a second wireless camera, also off eBay, for $80 give or take" and wire that one in yourself. Then you have two monitors to watch, but it might be easier.