I'm assuming these camera's use a reverse lamp wire as signal wire for automatic function? If so you can tap in at either side, where the taillamp harness comes in from the body into the taillight. Just remove the 3 access panels in the quarter trim panel, remove bolts and pop the taillight out, grip it with your hands and pull directly rearwards. Unplug all bulbs, mark them if you think you'll get them confused, but trial and error works too, then tap in there and feed it through where it needs to go. Though it'd be less work to just tap in where the reverse lamp output voltage is.
