Re: RV Storage.... please help
The pros is that it cuts down on bird crap, tree sap, dust and sun damage. The con is that if it flaps in the wind, it can be like sandpaper on the finish.
Undercover is far better, but harder to find and more expensive.
Clean out the black and gray tanks real well. Some people put a grill over the dump tube and leave the valves open. Clean and drain the fresh water tank and the water heater. Drain the water system as much as practical. Some people like to blow air through the system to get more water out. If it could get to freezing, fill the lines with non-toxic antifreeze.
Turn off the propane at the main valve. I'd fill the tank first, but I don't know of any real down side of not doing that. Shut off the refridgerator and block the doors open a crack.
Make sure the batteries are fully charged and full of water. Activate any battery disconnect switches or relays, or unless there are computers which need power to keep their memory, disconnect the wires from the batteries (labelling them to facilitate proper hook up next year). Set up some kind of trickle charge system. Options are solar panel, automatic generator start (this one gives me the willies) or a plug in system. Just plugging the unit into the wall may require monthly visits to replace any water boiled off in the batteries, depending on the type of batteries you have.
If it is a diesel, it will be unhappy stored that long. It would be better if you could take it for a 100 mile jaunt every other month or so. If it is a diesel, make sure the tank is as full as practical to reduce condensation of water. Add anti-bacterial and other additives as appropriate. Gas will break down quickly and needs something like 'Sta-Bil', but I don't know how often you need to refresh it. It is possible that draining the fuel system would be the best option, but almost certainly would be a major pain.
Make sure all automotive fluids are full and not too worn out. Plan to service them when you take it out of storage.
Probably should visit every other month or so and run the generator for an hour under significant load (AC generally would be best).
Wash the exterior real well to get any corrosive stuff off. Seal off anywhere that bugs could make their homes, particularly the vents for burners like the heater, fridge and water heater. Possibly air conditioner grill as well. Check all seals and do any roof maintenance which is called for by time or condition. Cover the glass with an external cover, particularly the windshield, to protect the glass and keep UV out of the interior (if not covered).
Make sure the tires are not on a surface which could damage them. It would be best if you park it on plywood or plastic pads. It might be nice to block it up so the springs are not compressed and not all the weight is on the tires. Make sure that anything which has springs has the springs as relaxed as practical. Cover the tires to protect them from UV (if not covered storage).