Going back to propane, it sounds like having a 1,000 gallon tank would cover you for a good, long time. At 50 gallons, that costs you about $100/day, and everything works as usual. That's not so bad, as long as it's not out for a month.
It seems like ANY system is going to cost you, besides solar. My little 300W portable solar panels top off my lithium batteries FAST on a sunny day. But in the winter, that may not work so well, with the shorter days.
I just saw a 10kW generator you connect to your tractor's 3 point hitch and just let her idle. That's an interesting concept, too. My tractor runs forever on a gallon of fuel.