I was told by a used RV salesman to avoid keystones. I asked why and she showed me front caps of some used ones. They were totally warped and leaky. He said many of them use just standard cardboard behind the front cap and just humidity from breating in the bedroom can cause it to warp. I don't know if this is true, but i did see the damage. Worst of all is the smell of the leaky ones.
Op sorry to hear about your camper. I will tell you one of the problems with manufacurers is that they most likely hire the cheapest labor they can get to build these things. The auto industry for the most part is built by machines yet campers are still built by hand. The quality is only as good as the craftsmanship hired to build them.