RE: Flux battery Minimum Amp question
Without onboard AMP meter there is no way to know the load while the truck is running, all you can do is monitor ESC and Motor temps to guess at the load. So yes a 20c Pack is a little light for 1/8 scale Truck on off road conditions, lowering your pinion would give a little headroom for Amperes if you already own the 20c's.
I shoot for 135 F on both Motor and ESC under heavy load for several minutes to ensure my batts will survive, WOT runs again and again for long distances give a good test for batts and Pinion combination. High quality batts can take abuse far better but I opt for thoses chinese noc-offs and am having great success at 50% savings in cost.