Ok, this may sound nutty, but can you charge while you ride? Sailboaters often charge batteries with a small, not too expensive honda ex1000 or similar generator. Could you strap one on and charge while you ride? Im sure it wouldnt provide all the power you need to run indefinitly, but it may be an interesting hybrid
"If you love wealth more than liberty, the tranquility of servitude better than the animating contest of freedom, depart from us in peace. We ask not your counsel nor your arms. Crouch down and lick the hand that feeds you. May your chains rest lightly upon you and may posterity forget that you were our countrymen."
- Samuel Adams