Greg, yup that was the bondo I was considering. I think it would work well.
Steve, I am not familiar with Lexel. I'll look into it. What I was thinking of using (if I did not use the bondo) was 3M 5200. Althought referered to as caulk in a previous post it is far from that. It is a polyurethane adhesive and has been used in the boating industry for years for hull to deck joints and underwater thru hull fittings. Some of the lesser expensive boats even forgo mechanical fasteners and just use the adhesive. This is not considered a temporary fix and if you have tried to remove 5200 you would know that. I have, and ended up having to use a propane
torch to soften it to remove a thru hull on a sailboat as I bent a 10" wrench trying to spin it out without using heat. If I used this stuff to put the belly band back on it would never come off again with out destroying the camper. My plan was to just fill the gap with it though, then use a less agressive sealent for the band.
Where do I draw my fiberglass experience from? 13 years of living on, cruising and outfitting an offshore sailboat. I also enjoy custom molding fiberglass parts and have extensively used both epoxy and polyester resins along with the associated fillers.
One last thing and I hope I do not offend, these campers were built to a price point. Given that, they are pretty nice and I am excited about ours. But, they were not built particularly strong (thin chopper gun fiberglass instead of hand laid glass, rivets instead of tabbing, OSB floors, and well, the way the belly band was done). Any of these would have raised the price of the camper, and in Scamps defense they probably did not think some guy would be interested in restoring a 28 year old camper. I am trying to rectify as many of these as possible in our refit.