RE: Hybrid power plant.
Would be neat, kinda of like a diesel-electric locomotive, with hybrid reserve power on tap.
Problems could be:
Size...hard to fit everything in a tank as is, now you need to add engine, generator, rectifier/regulator.
Weight...more weight needs more power means more weight (augh, my head exploded)
Heat...engine+generator+regulator+motors = toasty?
Efficiency...most small generators are pretty poor, and glow fuel isn't exactly cheap. Using $5 worth of fuel to generator $1 of electricity might be the situation.
Dunno how much effort it would be worth though. NiCd/Nimh Batteries are pretty cheap and robust and can be swapped in and out. Lipos give you really long runtime if you can afford them. Direct gas drive would give you lots of power, and fast pit stops (refueling instead of recharging).
Hybrid in a tank...what's the advantage? Guess it would depend more on the size of the tank, as that would change a lot of the variables...
I'd be interested to see where you go with this.
D.