Take every load you have in the house.. Every light bulb, every fan, every pump, microwave, television, cellphone charger, etc. Estimate how many hours/day you use it and multiply by the number of watts it uses. That is your load analysis. If you will never run a well pump off of batteries, and always run it off the generator, you can ignore that.
Once you have an estimate of how many watt/hours per day you will be using, people can suggest a size of battery bank and tell you how long between periods that you would need to run the generator.
Theoretically, you could run the whole house off of a couple 12V car batteries, but you'd have to run the generator every hour or so. Conversely, you could build up a nice 48V $5000 battery bank and maybe not have to run the generator for a week if you were very frugal.
If you refuse to do a load analysis, any help that people might try and give you will be a shot in the dark.
Lastly, the reason I recommend some solar panels is that batteries will self-discharge over time. You might be just fine leaving a set of batteries unattended for weeks or months at a time, but from what I have read about sulfation, I think it would be unwise to go from heavy charge/discharge cycles to unattended on a battery bank. Also I think it's going to cost you a fortune in propane to really get a good absorption charge in and I bet most people running a battery/generator setup are particularly hard on batteries because it costs like the dickens to have a 12KW generator idling away at 1KW to hold a battery bank at absorb voltage for two hours every time you do a charge cycle.