Is my generator big enough?

You can overcome your ethanol issues by using a fuel additive/stabilizer. Yes, stored gasoline can be problematic but glazed cylinders or glazed rings are not a part of that. Gasoline with ethanol added doesn't destroy power equipment engines, it usually clogs the main jet so that they don't start. Higher horse power outboard engines are a different story. The modified ignition temperatures have been tested and documented to cause engine problems. I have a certification plaque for power equipment that says I'm qualified to work on small engines, not necessarily to comment on them, though, lol.