I'm skeptical of your analysis. In theory (using manufacturer's recommended loads) it would probably work. The manufacturer does not count on having only half the threads engaged, and that's the issue with this setup. If one of those bolts pulls out, he'll be done in about a mile. To use your own example, what if you chopped the ends off your rear axle and threaded a track nut halfway on. I just don't see this getting you very far.
and the size difference in the bolts used vs. the axle looks to be more than 1/16"