Hey JWaller,
Are you aware that the Wisconsin DOT is refusing to register ex-military vehicles on the basis of being off road? Search "wisdot" in this forum and find lots of postings.
Here's the Wis. Statute they've used, 341.10(6)
http://www.legis.state.wi.us/statutes/Stat0341.pdf
It was meant to apply to "mini-bikes, go-carts, and all-terrain vehicles", as clarified in the Wisconsin Administrative Code.
Here's a link to a NHTSA letter of interpretation that's important to you.
http://isearch.nhtsa.gov/gm/94/nht94-1.78.html
The end of the second paragraph states that the US military can sell surplus vehicles to the public without the need to modify the vehicle to meet Federal Motor Vehicle Safety Standards (FMVSS) (NMVSS) requirements. Why that matters is that those FMVSS requirements ONLY APPLY TO ON-ROAD VEHICLES. No FMVSS requirements apply to off-road vehicles. There would be no reason for NHTSA to even mention FMVSS requirements if the vehicles were to be used off-road. The fact that NHTSA mentions the exemption is clear indication that NHTSA expects and intends such vehicles to be licensed for on road use.
While the responsibility for licensing vehicles rests entirely with the individual state, there is a direct correlation:
In 1966, President Johnson signed into law the National Traffic and Motor Vehicle Safety Act and the Highway Safety Act. These acts placed the federal government in the leadership role of a comprehensive national program to reduce the number of injuries and deaths on America's highways. To provide coordination and guidance for highway safety programs at the state level, each state created a highway safety agency, whose programs were to be in accordance with Federal standards and must be approved by the Secretary of Transportation. [Highway Safety Act of 1966]
In the interest of highway safety, state Departments of Transportation generally recognize NHTSA authority when deciding which motor vehicles are acceptable to register and operate on-road.
Good luck in your efforts, and if I can be of any further assistance, please feel free to contact me directly.
Paul Underwood