We used semi-fat tire bikes (3") tires on solid Motobecane frames with hyd disk brakes for search and rescue. We even had 20" bar Stihl chainsaws mounted on the racks along with medical gear and survival kits and lots of electronic radio gear/GPS. We never knew where we were going to end up or for how long and what we would need. Sometimes we were in the outback for more than a week at a time. They were literally pack mules powered by humans.
I have seen pics of Cycocommute's bikes and I wouldn't hesitate to hear what he has to say.