I bought a wired version 3 years ago.
Backup CameraShop around, you might find it cheaper.
It has worked flawlessly.
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You can see the camera on the 2nd step down on the rear ladder. I have it zip tied to the ladder. I remove it at the end of the season when it goes into storage.
I ran the wire down the ladder, underneath the trailer, encased in plastic wire loom and zip tied to various parts under the trailer then up into the front storage compartment. I then mounted the connector under the front storage compartment.
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You can see the silver connector installation on the truck, next to the license plate light on the bumper. Again, ran the wire through plastic loom, zip tied at various points. X cut a rubber grommet leading into the cab, ran the wire up to the large monitor. I have my monitor attached to a "coffee" mug that fits in one of my 4 cup holders between the driver and passenger. The passenger monitors when we are towing our Swivelwheel.
It may not be the easiest, but I have not had to buy multiple systems to get one to work. Too broke for that.