Advice? Little late, eh? Just a guess, but I'm thinking that you made the seller a very, very, happy guy. Delamination and rot are both referred to as "like icebergs" since only ten percent is clearly visible. Sounds like you willingly bought a rolling disaster. As for my second guess, I'm betting that you start digging a bit deeper into this mess, realize that you made a huge, but fairly low cost, rookie error, and start looking for ways to recover some of your "investment" before you coach arrives at it's final destination AKA, the scrap yard. Good luck.