Herpstats won't run off my generator, so have a backup control method. Even if it's just a rheostat. The freezer will have draw a lot when the compressor first starts and could stall a smaller generator, just make sure there's enough overhead power available for the compressor in the freezer. 5k is a pretty standard rating that will run most households, but obviously that can change for household to household. Might be able to get with less, depends what your loads are.