If it isn't essential to have that large of a drain hose? Would it be possible to reduce it by half an inch or so to eliminate the rub? It's tough to call without being on-scene and looking at the whole action.....
Stay in contact with the dealer and see what the factory does as a retro-fit. I hope you have more luck with Forrest River than I did, My design defect (3 months after new unit purchase) was settled with, "Tough nuts, caveat emptor, buyer beware."
"If everything seems to be going well, look around, you've obviously overlooked something."