Okay, I'll weigh in here though I'm probably going to regret it. I watched the video and read all the posts.
There will never be a bolt-on system without flex and there probably shouldn't be as the stresses have to go somewhere. I firmly believe that the flex I saw on the video was not out of line. The issue is with the truck manufacturers making the beds cheaper and allowing the flex to crush the ribs. The B&W Companion was designed when they used real steel in the beds. In retrospect, it would have been better for B&W to design a footprint to distribute more of the weight but who knew? And who knows what the next design change will cause even to conventional hitches.
I cannot explain the other structural problems that the OP experienced, but the rib crushing issue is more on GM & others than it is on B&W.
Thanks for listening.....