I pump the gas out of my tank at the end of the season and put in a few gallons of race fuel with Stabil Marine and a little Marvel Mystery
Oil and run it through the fuel system. I put a few bars of Irish Spring in each side pipe, disconnect the battery, and throw a padded cover on it until spring. Unheated but insulated and finished garage in NH. This has worked for me for years. In my old barn, I would put a tarp under the car to reduce moisture and put 2x4 sheets of plywood under each tire. I don't do that anymore.