mike,
what diameter brake rotors are you running??
maybe try larger diameter rotors..
larger diameter brake rotors will provide more braking leverage so this could reduce pad wear a bit..
also, maybe stop by your local bicycle shop and inquire about tandem bicycle brake options since they are usually more heavy duty..
here was a source for 10" brake rotors: (stock motoped rotors are currently 9"/203mm)
(http://www.bicycledesigner.com/bike-parts/bicycle-brake/monster-disc-brake-rotor-255mm.html)
and some reviews from users:
(https://endless-sphere.com/forums/viewtopic.php?f=30&t=63142&start=1600&hilit=washer#p1117998)