Well I full time now but before I started doing that I'd add Sta-Bil (more on that in second) in the winter.. I still ran the Genny 30 minutes under at least half load (actually 3/5 in my case) every month. but then I used the RV basically Daily even when in winter storage (For about an hour or two a day).
Fill fuel tank adding Sta-Bil or Seafoam about mid point during the operation
Now.. I also have a special outlet on the RV to power the house in event of a power fail (And a proper transfer system in the house) worked real nice every winter when Detroit Edison failed to provide.
Next: Sta-bil or Seafoam.. Back then Sta-Bil sold one formula and it was not all that good with modern adulterated gasoline (My rig is a gasser) SeaFoam was recommended for E-anything other than zero or 1... Today's E-10 did not like the original Sta-Bil.. Today Sta-Bil has an "E-10" formula. But I no longer long term store. I use full time.
E-1? If you are old enough to remember Standard Oil adds "My Advice Sir, Get De-icer" here in the frozen north.. They added HEET brand Gas Line Antifreeze to the mix in the winter.. That's Alcohol folks. bure Wood Alcohol . about 1 pint to 20 gallons or so. a bit less than 1% .. Just enough to prevent gas line freeze up.
I can tell you it worked too