If it were me, I would;
1-Get it up off the ground (blocks under frame and weight off the jacks)
2-Tires off and stored inside somewhere away from sunlight
3-Winterized (if it will get below freezing)
4-Rodent proofed (dryer sheets, moth balls, holes to the inside sealed etc.)
5-Some sort of moisture absorbant and maybe leave a roof vent cracked for ventilation.
6-Seal off the exhaust ports for the HW heater and furnace
7-Have someone check on it periodically and replace the rodent proofing, dryer sheets or moth balls
8-Remove the battery and store it in a warm dry place and keep an automatic trickle charger on it to keep it charged
If I missed anything, I'm sure someone else will add to the list.
P.S. Why do you have to store it for such a long period?