those calculations look actually pretty good. the batteries are 1lb each, so 96lb worth of batteries. less than a passenger.
each battery is 72WH (or just under), so that's 7kWh from the batteries. so 2 hrs of flight at 3kW.
the real question is, is 5hp enough to take off on? I'd be pretty scared of how slowly it accelerates on ground roll.
ozzie: I'm in the hunter. want me to electrify your Lazair?