I am in the process of changing the flooring in my 05 mountain aire (gasser). The old carpet came off with out to much difficulty but now I have to deal with a type of vinyl material the manufacture...
Try to remove some of the vinyl flooring and see how it comes up. The adhesive may be weakened with heat from a hand held hair drier. If it is 3/8" thick, you may be able to take a circular saw and adjust the blade depth to help cut the flooring in to manageable strips for removal. I would suggest that before you put down your new flooring that you put a couple of coats of polyurethane on the sub-floor to seal out any odors and to help protect the sub-floor from any leaks/spills.