We do use additives.
I got a little pump this summer to get bad gas out of an old riding mower that’s been sitting. It works great - prime with 2-3 strokes & the gas starts flowing.
My dad insisted on keeping our generator full all the time (largest portable you can get, 17,500 watts, 15 gal tank). Since we weren’t running it enough to use what was in it in a reasonable amount of time, the gas separated & the generator wouldn’t start/run. I found someone to come work on it - he drained the tank, changed spark plugs, etc. All was well until ...
This summer when Ian hit FL, dad was afraid we would get some remnants, so he filled the tank. No Ian remnants & here the generator sits, full again. So, after yesterday, not so full.
In general, we fill 5 gallon cans to keep on hand if we need gas for the generator, but after about a month, we recycle by putting it in a vehicle, then getting fresh gas (& we put additive in the cans).
Where do you get ethanol-free gas in sealed cans? I know you can get ethanol-free gas at marinas, but we don’t have any within at least an hour’s drive.
Some premium gas is ethanol free. Ask your small implement dealer, like a John Deere or Stihl dealer. They will know where to get ethanol free gas. I have a gas station that has one pump for it.
Additionally if you fill the tank, just add stabilizer to the tank first so it mixes well. That will prevent phase split. Run such tanks for two hours twice a year.
Lowes, Ace Hardware and Tractor Supply (in my area) carry TruFuel by the gallon.