How long is a piece of string ???????????????
Its one of those jobs really, some mount to top of rear wall and run cabling down thru cupboards and underneath for the run to the draw bar while others have them mounted on a post above a rear bar mounted spare so depends on your configuration at the back.......
On my 14.44 I mounted it on the rear wall above the bed end, running the cables inside and down thru the bed end cavity to underneath, not something I would like to do again, trying to get the cable to feed inside the wall was bluddy horrible. No bed end, then inside a cupboard would be the shot... I picked up power from a stray 12v wire at the back around the tail lights, ideally using the 12v fridge power supply is good as it will only be active when hooked up, draws bugger all power so not a biggy, also shows when power to fridge drops off as so does Cam...... bonus.
Since I had spare pins in my 12 pin I used them for the 2 cam feed wires but eventually made up a dedicated socket using a 2 pin mike socket from Jaycar, works well. The supplied leads needed a bit more length so I replaced them with a long HDMI cable, just cut the plugs off, perfect for the job and has extra cables if other feeds are needed for some reason.... I only used a 2 wire run, could see no need for audio..............
Anyway have a good look around on here as there are some threads about it and with pics.
