I’ve got my from camera plug into the USB-C port at the rear of the front seats then cable routed under the carpet and tucked into the headliner up and over to the centrally located camera. Rear camera was simply getting a USB adaptor for the back 12V socket and pushing the cable into the rubber seals around the back door at high level allowing a bit of slack for the opening and closing of the door. No cables show inside the passenger part of the car itself and is all above board with Motability.
My grandson bought me a hardwire kit last year but I’ve never used because of Mota rules. I’m not 100% sure as to why they don’t like hard wiring as piggy back fuses do no harm to the car itself but I assume there fears are more to do with electrical fires(a top subject in the news of late) no matter what starts them having a camera hardwired gives their insurers a get out of jail free card, just imagine burning down a car park ? or should you look out of your window one morning and see your car has been burn to a crisp.