No problem, I just hoped we hadn't chased you away. As you can see, there are many ways to skin this cat, and it can be done pretty simply with what you have.
With all that's been said, I'd have to lean to the AA NiMh batteries and holder in a boxcar, that would make it painless to run and recharge. A $10-15 charger will recharge them, and the batteries are cheap as well. I'd probably want 12 batteries to give me 14.4 volts, that would work pretty well. Those should fit in a boxcar, and you could rig it so you just pick the shell off to change and/or recharge the batteries.
