[starscream]

Runtime depends on driving style, type of BL System, gearing, & voltage, as well as the weight of the vehicle.
What motor and esc will you be running on the Revo?

If you run lipo, you should use a low voltage cutoff device to keep from destroying your investment.

45 minutes is a long run so you'll want to keep the motor temps down. I'd invest in some additional fans. Seeing how the gas trucks will need to re-fuel around 3-6 times, if you only have to change batteries once, you could be fine. You just need a battery configuration thats easy to swap in and out. A single pack lends itself better for this IMO.

You will most likely need 8Ah's to make it through the 45 min A Main.

Good luck, go get those nitro's ;)