I got a TRI-Fuel generator a few years back, it cost $1600 then, they are up to about $2000 now. I would never get rid of it. It runs on GAS, PROPANE and NATURAL GAS. I have it hooked up to a natural gas line, but I also keep gas in the fuel tank. It is easier to start with gasoline and then I switch it over to natural gas.
Using anything with a fuel tank leaves you the possibility of running out of fuel before the power comes back on. We have never been without natural gas where I live. But I have been snowed in so deep I could not get out for 3 days! Had I been running on a regular gas generator I would have run out of gas in a day or two, even with a couple spare gas cans. Had I been running the power off the PTO, I would have not been able to clear the driveway, let alone a section of the road. It took a bunch of us working to get a passable path in the road so we could get out to the county road, only to find the county snow plow stuck in the ditch!
If you want to power a house, don't tie up your tractor at a time when you might need it the most.
My generator will power the well, the furnace, the microwave, the refrigerator and the lights and TV sets, but I cannot run the AC in the summer. I run a 4000 square foot house with an 8KW generator. You can set up an emergency panel next to your circuit breaker with all the key cirucuts you NEED to power and you can get by with a generator about 1/2 the size you think you need. Pick the critical circuits and size your generator for those power loads.
To run my set up I simply flip one switch to take my house off the utility grid and onto the generator and then I turn the electric start on the generator to fire it up. The house powers up and the utility cut off prevents any of my excess electricity from traveling out onto the power grid and electicuting any repairmen working on the lines!
