How to mount backup camera below running lights

[ILoveRockies]

I bought a wireless backup camera for my "new-to-me" 2720QB and want to install it on the back of the camper just under the middle running light. It will be wired to the running light. What is the best way to do this. I'm thinking about gluing a small piece of plywood to the shell with PL400 then screwing the camera to it. Or is it OK to screw it directly into the shell and applying silicone sealant around it?

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