Another 11 miles with a heavy payload shredded the shoelace coating & burned 360mAh/mile.  Interestingly, 11 miles with a light payload left the shoelaces intact & burned a record low 286mAh/mile.  A fabric coating might have much lower rolling resistance than rubber, though insufficient life.  It also might be the fabric which shredded wasn't covering the entire contact area, so it was getting lifted from 1 side.  

If money was infinite, experiments with kevlar fabric could be justified, but the next focus was garden hose rubber.  It couldn't conform to the wheel at all & was much heavier, so the lion kingdom tried tiles.  Any rubber pliable enough to conform to the tire is probably going to be too easy to shred.  Kevlar coated tires just sound badass & might actually work.

There's enough E6000 in the $4 tube for 1 more coating.  The E6000, liquid electrical tape, shoelace, & hose rubber have already been far more expensive than just buying new tires.