I'm going to give a contrarian view to what others are saying... I've never felt the need for even a jerry can, and my range has always been <300 miles. It's never been an issue. Mostly western US, but also Baja and southern CA. If you are in Australia or plan to explore N CA, or someplace else in the world, your needs might be very different.
Gas is heavy, so I don't understand the "you can never have too much" refrain, especially with a payload challenged rig. There are 1,000,000 other things with far worse consequences than running out of gas that can go wrong in the back country. At any rate, I've never run out.
Find a good site that is unpopular and park it for as long as you want! Technically 2 weeks is the limit on NF and BLM before you have to move some distance, but you'll probably be needing supplies then anyway.