Has anyone any knowledge of what structure is behind the rear exterior fiberglass wall on the RV. I called CS and they told me the only structure was at the ends of the rear window going vertically. However when I use a basic stud finder I do see the framing at the window corners but I also get a reading at the center below of the window - seems there might be a vertical beam or support of some type there? Want to mount a GM rear wired camera below the rear window as recommend by GM and just wanted to see if anyone else has had any experience with this. Thank you