Generator usage for most RVers is sporadic at best, and for many who go from RV park to RV park where power is provided, are not used at all. If you have electric provided at your nightly destinations you will not use the generator much at all and should not pose a significant budget concern.
Your RV fridge will have an Auto feature that when plugged into power pedestal at RV park will cool fridge off of electric, when you unplug it will automatically revert to propane to cool fridge. Your RV fridge uses very little propane to keep everything cool inside.
Sure you may run into some situation where you need to run your microwave or AC for brief periods while traveling down the road or at a roadside stop, not something I would budget more than a few hours weekly if even that. For us that amounts to maybe 10% of our total usage.
In our case we do use our generator frequently as are preferred method of RVing is dry camping or boondocking. Even so it is sporadic most occasions, although we have run into intense weather where generator usage for us peaks. The vast majority of RVers do so without owning a generator at all.