Hopkins Smart Hitch

Looks like you need to be able to plug into the round socket for the factory tow package. The cool thing is that this appears to go inline with the 7-pin Bargman for those of us with the factory HD towing package.

But with only the 4-flat connector, not sure if this is for you.

[EDIT: I just saw the instructions, and see what you plan to do. You will cut off the plug to the tow package, and wire directly to the reverse lights. Note, this means the screen will only be on when you are in reverse.]

Hi thebrakeman. Yes thats exactly what i did, in fact i spent most of Sunday doing it!! lol I practically removed every panel of the car, in order to wire the thing up. Put the screen on the "tray" behind the stereo, the cable then goes into the air vent (that only section of cable that is visible) then down behind the stereo, across the drivers side (under the carpet) then down the left side of the truck, behind the panel covering the rear left wheel, then connects to the Reverse light wires (after cutting off the 7-pin connector) then up around the door frame, through the rubber tubing to the back door (the trickiest part of the install) then around the door and through the grommet with the wires for the license plate lights. Works great, as soon as you put it in reverse, the screen comes on and the sensors are active.
I would recommend it as a fairly cheap mod, that doesn't involve cutting/drilling or any actual physical change to be made to the truck. (the only thing i might change, is behind the screen, I might drill a small hole through the plastic "tray" so that the cable could go though it instead of the air vent, then you would not see any cabling anywhere) If i sell it in the future, would be easy enough to remove it and use it in my next truck. To be honest, wiring it in this way would mean it could be used on any vehicle, not just trucks with the Trailer hitch.
Sorry if that was too much information lol!
Cheers