Brushless motor/ESC combo??

[Bondonutz]

Part of the problem is if you go brushless, the ESC's and motor demand lots of amps to run properly. If your basically gonna crawl you'll still torque, to get that power you'll need voltage and amps, I would recomend at least 11volts 9-10cells of NiMH or a 3s lipos at the very least. Again, ideally 14.8volts will not be to much power for what you want to do, you can gear down or set the EPA on your TX down a bit to compensate.
Your truck will weigh close to 8-10lbs, the higher voltage (14.8) will help run much more efficently than what your talking about doing with a single pack.

The smaller crawlers, Axials etc can run a single pack because these trucks are 1/2 the weight or less than your maxx.