If they have flat spots ? Check the brakes . Rotating tyres to me is a way of overcoming / musking wheel alignment issues .. So you wear ALL the tyres out !! Find what is causing the wear ?
Last van sat in drive for near 5 yrs and never moved. Just checked pressures occasionally.
They towed it down to Melb ok. (3 ton 6.5 mtr Off roader, Bridgestone A\T 10 pr)
The only chassis likely to "warp" if jacked. For any length of time.
Is either VERRRRY old. or verry cheaply built with below reg's steel.
Normal regulation chassis section won't be a problem mate.
and for a coupla months.
Just blow them up to 45lb and forget..
I had to leave my van and tug parked up for 20 months a couple of years ago, and was concerned about the same thing. Once on the road again no problems.