Another 10.85 miles with dual batteries burned 3441mAh + 3766mAh or  664mAh/mile.  Far below brushed motor range & half the rebuilt transmission range.  It wouldn't even make it to the last vending machine or the Alamo.  By the end, the weight of the 2nd battery had the tires skidding around the wheels again.  This was the same pair of tires which skidded before.  It traded places with the front tires, which stopped the skidding, & was rotated back to the rear because of wear.

Steering was solid.  Rebuilding the entire drive train & replacing the tires is a lot of work. Front tires might benefit from another toe out.

Toed out another turn & went another 11.1 miles on the same route in reverse, with the slipping wheels.  That burned 3258 + 3618mAh or 619mAh/mile.  A dramatic improvement, relatively speaking.