First, here's how I setup my previous tow vehicle with a backup camera, and how I added a backup camera to the travel trailer:
http://www.2manytoyz.com/backupcam.htmlMy F150 has a built-in backup camera and monitor built into the mirror. I didn't want to put an external monitor on top of the existing one.
A little research on the Ford forums and I found the wiring diagram for my specific vehicle. I tapped into the video camera feed lines going to the tailgate camera, and added an external video connector.
I use the OEM camera when hitching. Once coupled, I disconnect the tailgate camera, and plug the video feed cable from the TT to the new connector I added. Here's the result:
In the reflection of the mirror, you can see the camper still hitched, but in the monitor, you can see what's behind the trailer.
A few downsides with mine. The monitor window is small, but functional. I have to climb under the back of the truck to disconnect the OEM camera cable. The monitor is only active when in reverse (I might tap into the monitor trigger wire to fix that).
Compare that to the size of the aftermarket mirror/monitor I had on my last tow vehicle:
Again, the camper was connected. What you see is another vehicle parked behind our trailer. The same video camera on the trailer was used in both pictures.
And I even used an external monitor when the aftermarket mirror one failed after years of use.
I still have this one, and considering using it. Far better resolution than the built-in monitor, and can be connected to 2 cameras at once. Simply push a button to switch between views. Easy to have it powered up all the time. The shifter is offset in this pic, and wasn't in the way for the driver, especially once in gear. The downside is it takes up valuable room.
Good luck with your project. It certainly IS doable. Just need to find the wiring diagram for your vehicle. Be sure to disconnect the existing camera when using the TT camera.