Good point, ykick, about the long-range capability. If you filled the triangle and the case with lithium, as you said, it would go far. Add something to that rear rack as well and you could probably go all day for a couple hundred miles, plug in at a motel, and continue the next day. I bet you could cross the country in two weeks on one if done right (depending on tires, flats, people throwing crap at you, etc. on the road).
But if I were going to try to cross the country I'd use a recumbent and load it up with batteries. It would be more comfortable.