This seems to be a well-known problem, and I have even seen new campers on the dealer's lot with broken rivets or trim falling off. Why the factory hasn't clued in and fixed the issue is a mystery.
That is one of the first things I reinforced on our new fifth, as it was obvious it wouldn't last.
dunnnc, your mod looks pretty solid, you could probably sell a few sets right here! Are they tig welded?