In search of minimalism (which would appear to be essential given the goals of the endevour), I would suggest replacing the air tires with solid rubber. They will not absorb shock as well, but you don't have delicate instruments in it, and while they will weigh more individually, they will allow you to eliminate the air pump and the tire patch kit and actually eliminate any energy expenditure in repairing tires.
This is an interesting mind experiment of its own! Want to label it #3?
Cheers,
Buffy
