I've done more laying up of motorcycles than 4 wheels, but no one else has jumped in here after a day, so ........

What I have done is drain the fuel tank and carburettor and spray the tank internally with WD40 to stop rusting (this would not be too easy with a 4 wheeler of course, so maybe consider filling/brimming the tank to expel air - with diesel hopefully, which is somewhat oily, rather than the more volatile petrol).

Use ACF50 spray on the bits that are liable to corrosion, such as the engine components.

Assuming that it is under a roof for protection from the weather then use a lightweight dust cover (for motorcycles there are "air bags" which envelope the whole bike and then the air is sucked out with a vacuum cleaner, or similar, to provide an airless environment, but I have never heard of these in larger sizes).

Disconnect/remove the battery of course, or have a deal with someone to turn over the engine every now and again including bringing the engine up to working temperature.

Drain the old oil and then refill with brand new oil? (on the basis that the new stuff is less corrosive when standing still).

Regarding your specific idea, I have only ever seen military vehicles blocked up so that the weight is off the tyres; that was intended for the sort of duration that you are considering.

Maybe get the underside waxoyled?

I hope this is of some help.

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Dave