I have the wiring diagram someplace that shows where to pick up the backup light circuit. That's what I might do (go to 5th wire) when I get tired of jumping out of the car to put the backup pin in my surge brakes.
On my Santa Fe I ran 2 #10 's from battery via circuit breakers and relay to the trailer connector as power for wireless brake controller and charge for trailer battery. Works well. Will probably do same with whatever I get as it seems all CUV's are only 4-pin.