Winterized my toy-hauler. . the one good thing about it is the cars we have got about 12 gallons of gas from the trailers gas tank... Used sta-bil for the rest.
Have covers for the wheels and A/C's on top, blew out the lines and drained everything. . I am going to keep the batteries (4 golf cart in box and on plastic). . in it as I have a solar Panels that can charge up to 7 amps.
Even with snow on the roof sometimes, it melts, and then the batteries charge back up. Be good to have the batteries in there, in case we need it for power outage, etc.