I have a rear camera installed, the camera is bolted to the rear parcel shelf, using 2 holes drilled into the suction housing.
The cable is then routed across the rear shelf, down behind the offside rear seat, then under the rear footwell carpet and up into the centre cubby box, into the rear power socket.
If I need to remove the shelf for any reason, then the cable simply unplugs from the camera, obviously the camera can’t then be used, in this situation.
As others have said, it would be very difficult to stick the camera to the rear screen and route the cable under the headlining, this method is I think a compromise.