It is a long drive to my training grounds. But I do live very near a terrific trail system, and have been running dogs there on checkcords (no off leash dogs, and no four-wheelers, dammit). My usual loop is about 6 miles.
I have contemplated using my mountain bike to road dogs, but two dogs and a mountain bike = scrapes and scars. While thinking about a simple way to road at full running speeds, I searched up this dry-land mushing cart. Built by Arctis in California, this cart or something like it would neatly solve my problem.