As a non steam man, my suggestions would be.
Spray oil into the steam chest and cylinder, and then fill the boiler the top with 50/50 antifreeze solution., to benefit from the inhibitors, and the risk of frost damage. Drain and flush out before steaming next season!
Oil/grease all bright metal work, cover, but leave the bottom open so that any moist air can fall out.
Through lack of space my bandsaw lives outside. The bare metal is oiled from time to time, and the "box" cover is made of the same material used for curtainsider trailers, with the bottom open. Rust is not a problem.
Howard