Not RV, but we haven't had a good generator bashing lately.

Adding fuel stabalizer is good but running the carb dry is really the bigger thing.

If you lay it up properly, really no need to start it every 90 days. Had a 30yr old boat that sat 7-9 months per year and always started up fine and ran strong. Couldn't drain the tank as is was 220gal and buried in the hull.

Ideally, I would run it empty and then keep a 5 gal jug of fuel next to it...and every month or so, dump the 5 gal jug in the truck and refill the jug with fresh.