Diagnosing Lippert Frame issue with my Cougar

I had a frame flex issue with my Heartland Sundance, which also uses Lippert frames. The factory had to seperate the front cap and peel the outside skin back about 3ft on each side to expose the aluminum frame inside the walls. They found and repaired broken welds there, and braced up the steel frame with large gussets.
Mine was also showing flexing at the pin while towing. I could not see any movement inside like your pictures show but the trim on the outside of the trailer was seperating and closing when hitching and unhitching.