Wow, it is a shame that Winnebago hasn't improved that bonding technique over the years. I had both the rear lower clip and the generator access door on my 2002 Winnebago Journey start to fall off. In both cases, the bonding agent lifted from the metal brackets since the brackets were painted and there was no evidence of any prep (roughing up, etc.) of those brackets.
I had a friend who owned a body shop re-attach the rear clip. He roughed up the brackets and used some sort of body shop epoxy. I later repaired the front genset access door using some JB Weld but I also added four stainless button head bolts. It looked fine IMO.