RV gasoline life span in long term storage

Without stabilizer and with ethanol, "over a year" is not good.
It kind of depends on how much over a year......and what the quantity is.
A large tank will fare better than a small one.

Sorry to hear about your difficulties. Was any fuel stabilizer used prior to parking? If so, it’s probably OK, but I wouldn’t personally go past two years even with stabilizer.

If it was not treated, it depends on the conditions, temperature, humidity, how full the tank is. Over a year could be to the point of degrading already. If it was mine, I’d put some Techron fuel system cleaner and some octane boost in the tank and hope for the best. Probably that will get you through that gas and you can drive it out and get fresh gas.

It’s impossible to be certain of the situation until you get into it. Could be no problems; could need fuel filters, worst case it could need the tank dropped and drained.

Stabil states 2 years.

You'll be fine. How long do those unwanted new cars on the lot sit before they drop the price in half?

might be ok, pour a couple cans of sea foam in it and drive it around about twenty miles. then use that fuel up as soon as you can.

I had a classic car that did not get driven too often (<150/year); it
had at least 2 year old gas in the tank and drove ok each time.

However - it sat unused for more than couple of years and the float bowl
and jets had a chalky residue which had to be cleaned out.

If you can; run the engine to operating - every once in a while and maybe
add fresh gas with seafoam.

THe answer is I DO NOT KNOW.. but I can tell you this.....

They say more than six months unless you stablize is asking for trouble

I know of a Workhorse 8.1L Fuel injected Vortec that sat for several years. So long the batteries were flat (Would not even taker a charge) Took 3 of us and the converter to bring in the slides. Dropped a new chassis battery in it turned the key and it fired up like I was in the dealer's showroom. Drove it around the campgroung a couple of times and parked it in the long term storage area for the cg owner (This was done with premission of the RV owner) Never misfired, not once.

Of course I also never hit 10 MPH

when I worked for big box store they always said 30 and it starts going bad. that is why in the spring they sell a ton of lawn mower carburetors

Does not say what State it is stored in. If Calif I would not trust going over 60 days at the most unless you have Stabilizer or seafoam in the tank

How much fuel is in the tank?

If it's on "E", consider draining and disposing of the old fuel if you can get at the outlet easily.

Otherwise, you can dilute with fresh gas.

On the positive side, if it's a full tank of gas, you are less likely to get water in the fuel but be prepared to swap out filters if there is water in there.

Unless it's a really old MH, I expect it has fuel injection so the float bowl and carb jets gunking up are likely not an issue.