On your license plate camera, regardless of where you mount it, before you install it, take out the rubber plugs on the back of the camera unit which are hiding screws underneath, unscrew the screws, and pull up the plastic rear cover, and put plenty of silicone all around the mating surfaces. Then reinstall the cover and put some more silicone around where it attaches and make sure it seals up tight. Everyone who has had these has had water build up on the inside at one point or another. Trust me, I live in Nevada where there is next to no moisture, but it gets in anyways. I sealed it an blasted it with a pressure washer for several minutes straight and no moisture build up at all.