I placed mine onto a holder screwed to the license plate, with wires coming through the interior of the rear door. In the cabin, the wires enter from above the headliner, then go through the rubber wiring hose between the body and rear door, which is a huge PITA to fish it through that tight hose, but worth it if you want a clean look. It also requires you fully removing the rear door's "door card" so that you have access to the interior of the rear door to fish the wires through and down into the license plate area.

Mounting internally behind the rear door glass will give you huge blind spots due to the spare tire, but does have better dust/water protection.

https://www.printables.com/model/124...camera-bracket