I realize this is a dated reply. But, I still wanted to reply to it.
I abandoned this I think the day I posted it.
Why? I think it would have been a great idea, especially since you have a dual fuel generator.
But I couldn't make it work. Very frustrating.
Have a look at the following YouTube video.
LDSPrepper, whom I have been following for ages, move from his former home, to Idaho. He purchased 2 - 1000 gallons LPG tanks and put them in the ground.