Drill the hole for the mount point for the camera.
This is what it looks like from the inside. Note, the square opening is factory cut. It's a little tight, but still big enough to allow for the install.
Mount the camera. I put some shoe goo between the camera and the car to make sure it doesn't shift if the bolt loosens.
Run the wire from the camera towards the hatch conduit. Connect up the camera wire to the wire from the HU. See the tie strap I did on the connection. This prevents the connection from coming loose if there was an accidental tug on the wire.