Not knowing the specific coach, I can't really offer a solution other than taking other things apart to get it out. Is it possible to measure the tank and then measure (or estimate) the size of the opening without the frame to make sure it'll work?
On mine, the only think I've removed from the basement was the Aquahot system. I will say that the opening was only around 1/16" extra on each side to slide it out. If I had removed the gasket around the opening, it would have been a bit easier. Therefore, I can imagine that yours will be just as close.
2007 HR Scepter 40 PDQ
400 ISL, ~67K on the clock....for now