Recommendations for Parking Surface for Diesel Pusher

Any surface you park on is going to allow moisture up around the tires thus contributing to dry rot of your tires. This includes dirt, gravel, concrete, wood and any other porous surface. Place the tires on metal such as galvanized or aluminum roof flashing. Plastics will work for you as well. Place mats of plastic or cutting boards, etc.
Jacking the vehicle up so the tires clear the floor works too. Get some sheet metal scraps from the local tin shop. Those will work too.