I am not familiar with construction of the view, but most Winnebago coaches have "sandwiched" sidewalls (fiberglass sheet outside/Styrofoam w/aluminum studs/inner wall material. The rear cap is a molded piece of fiberglass, NOT laminated. Of course, there is a rear wall under that cap that is the real structural integrity of the "box". The cap is simply fastened over the rear wall.
I would want to determine if your rear cap is coming loose, OR if the rear wall itself is separating. Can you get to the rear wall corners inside the coach to check for a gap there? If there IS a gap there, the rear wall is separating. If the is NOT a gap there, it is simply the rear cap coming loose (not desirable, but not as serious as the wall separating!!). If you can't see it ...and even if you can ...you will likely need to take it to a dealership who can diagnose & handle the problem.
I have had good results over the years in sending digital pictures to Winnebago Owner Relations asking for their recommendations in both the fix AND for a dealer in my area who should be able to handle the problem. That also would give them an opportunity to see if you may have a manufacturing defect. Their email is
[email protected] ... telephone is 800-537-1885.