That is very cool. If you want a bigger hauler, try this one from Komatsu.
http://www.equipmentworld.com/komats...-truck-no-cab/
Similar look, no cab, and goes just as well in either direction. The limiting factor in the Komatsu truck is tires. It has the largest ones currently available in the world so if bigger ones are ever made, this design could go bigger.
Ken