I've been looking into backup solutions to keep my fridge and well pump [1] going during outages. Anyone tried something like the following?

The obvious approach is a propane generator. Propane rather than gasoline because we only get a small number of outages a year, and most are fairly short, but there is occasionally one that is 10+ hours. I'd want to store enough fuel for at least 10 hours of generator use, but most years would only actually use a fraction of that, and so I'd have to be constantly rotating the fuel (probably into my car, as the only other gas powered thing I have, my lawn mower, only uses about a gallon a year) to keep it fresh enough to still work for the generator. Propane does not go bad, so storing 10 hours worth of propane for years is no problem.

But both of the things I want to power (fridge and pump) are very intermittent loads. I don't want the generator running all the time during an outage, wasting fuel, just to be ready when the fridge or pump needs to actually run. Even idling the generator will be consuming fuel. I could leave the generator off except when I need to actually have the fridge or well run, but that would be quite annoying as I'd have to go outside to start and stop the generator--and power failures are usually when it is quite unpleasant outside.

So what I've been thinking of is having a dedicated battery and inverter for the fridge, and a dedicated battery and inverter for the well pump.

When power fails, I can start watching the fridge temperature (it has a battery powered wireless temperature monitor, so I can see the temperature without opening the door). When it warms up to the high end of its normal variation, I can unplug it from the wall outlet, plug it into the inverter, and start the inverter running off the battery. When the fridge cools back down, turn off the inverter. Repeat throughout the outage.

Similar for well pump. When I run out of water, go run the pump from the inverter and battery until the tank is full.

I'd still have the generator, but now it would be used to recharge batteries, not power any house circuits or devices. Over time, I'd probably add batteries, eventually reaching a point where I have enough that I can get through most outages without needing the generator.

(Actually, I'd probably do the well directly from the generator instead of inverter and battery. When I go out to turn on the generator to recharge batteries, I'd also plug the well pump into the generator to refill the well).

I could start with one inverter and a battery or two, without a generator. This would probably get me through a large fraction of the outages. Then over time I could add more batteries, more inverters, and the generator to extend the number of things I can use during an outage and how long an outage I can get through, in a nice budget friendly way.

[1] I probably don't actually need the well pump--as soon as an outage starts I fill a couple water bottles to have drinking water, and fill the bath tub to have water for flushing the toilet, and that will almost always be good enough. Why immediately fill things instead of just leaving the water in the well tank and hot water heater until I actually need it? Because I have no idea how much water I have. The outage could have happened right after the pump finished filling the tank, or it could be just before the pump was going to start and fill a nearly empty tank. Filling the water bottles and bathtub right away lets me know what I've got.