What is going on here!? I noticed the rear side wall starting to separate from the core and look like a wave earlier this spring and have been watching it, then I just noticed this crack before leaving this weekend for a trip. I'm really disappointed to find that the skin is glued to plywood??? I was under the assumption from all the research I did before choosing heartland that the exterior walls had a foam core that was compressed. Why am I looking at rotting plywood? Please explain why it is constructed like this and how this can be fixed.