Chalet with a rotted basement floor

So sorry to hear of your problem. It sounds more like a major structural failure in the floor area. Its hard to imagine that you would have that much rot in just 2 years, plus like you mentioned I would think you would of seen signs of water leakage at some point during its use, especially to cause that much rot in such a short time span. I hope you can find a solution. Being I also live in the east I can feel for you and realize how inconvenient a repair trip to the factory could be.
Maybe try someone like Truck Camper Warehouse in NH (also a location on Long Island) since I know he is very familiar with TCs and he sells Chalet. Plus he does do some pretty major repair work.