reversing cameras usually point about 45 degrees to the road, not stright out, so that you can see how close you are getting bumper to bumper
so i would mount it inside the hollowed out bit under the bit that goes above the number plate, this should mean you can mount it central. As you dont want to mount it off to one side, as that will make it harder to gauge distances! also, too low and you wont see anything for long!
OEM ones are mounted in similar places, unler the grab handle, just above the number plate
wires, would mean drilling a hole into the boot lid, and then id trace them from the inside of the bootlid, up the side of the rear window, and than along the hinge. From there you could go down one of the pillars to the floor
Personally, id trace it along inside the head lining, and down the A pillar, then behind the dashboard. Means you wont see any wires anywhere!
But then, i wouldnt bother seems a lot of trouble for something that isnt needed :chin: