Securing observation camera to back of TT

It’s a wired system.

How are you powering the camera? Aren't you drilling a hole to run the wire to a marker light? Personally, I wouldn't worry about a couple of small holes, just seal them with a little calk.

I've been using 3M double sided tapes since the '60's and that stuff really sticks!

I don't think you'll have any problem using it for a light weight observation camera. If the camera has much weight to it though, you'll have to revisit this question.

BTW, there's really no problem drilling holes in fiberglass since you'll be doing it on a nearly vertical wall in the back. Just put a short strip of stick on gutter over it to route water away and you're good. Oh, and silicone or Eternabond tape around it too maybe. Depends on the camera and where it's mounted.