storing an RV

Not your question but I would want a dehumidifier running inside to prevent mildew.

Thanks everyone

I used to own 1972 Prevost conversion that sit 8 years before I bought it and then in my 12 years of ownership it would sit for 2 years.
The only thing I did was taking engine batteries home and keep them under battery maintainer unless I put them for different use.
Golf-cart batteries would keep charge (when disconnected) for a year just fine.
Gasoline engines are a bit different story as evaporating gasoline can leave gunk behind, but FI should be safe for couple of years if the tank is pressurized.
RV owners are always paranoid about their vehicle maintenance.
Me? Even I am not a farmer, I like the farmer's idea about winterizing their equipment.
"disconnect the battery, put coffee can over the exhaust and walk away"

Can I use it for next 13 months?

Stabilizer only helps for so long. Having said that I've left a MH sit for more than a year. First tank will not give you good mileage but should improve with fresh gas. If you want to have it serviced wait until just before you're ready to go. Don't start it, don't drive it unless you're going to drive it enough to really warm it up, engine, exhaust and trans. The worst thing for an engine is to start it and not drive it enough to get it hot to dry things out. A by-product of exhaust is condensation. Do exercise the generator every month or two under a load, A/C, heat pumps or etc. The generator brushes and contacts can corrode if not exercised with a load. If they do corrode your generator may be useless until it's taken apart and the corrosion removed.

Good to go. I would hit the open road before it was fully warmed up and just keep rollin'.

I would check out everything now rather than wait till the last minute and have to scramble.

Sounds like a huge waste of money. Why not sell it?