I think your first instinct to walk away was right. Hell, maybe run away. Sitting unused for years is not good for a machine with as many systems as a motorhome. Things just rot. Was that engine ever serviced before being parked? Most likely not. That entire end cap needs replacing and whatever else he ripped up. $$$ and headaches. There must be a whole buncha used rigs for sale down there in retirement land. Look some more. Take your time till you find the right one.