Just run a 12V feed to the rear that is switched on with the ignition. That's what I did on my Mazda 323 for the traffic camera. Did it after an insurance dispute when some one reversed into the wifes car. You realy need video evidence these days.
-- Edited by DeBe on Friday 7th of September 2018 07:10:24 PM
Pretty much your best option is to run the 12 V from your ignition to the rear. You are going to have to run the video feed anyway.
Too many stories about crap vision with wireless cameras to contemplate that route.
Being lazy & a tight arse I began with cheap wireless only to find too many hassles with reception, so I removed the wireless gadgets at each end and ran a video feed wire. I need a cheap 90 or less degree camera to give me a more "real life" look out the back.
Everything on this van is done "cheap" for proof of concept purposes so I know what we really do need when we go away for some major gallivanting.