Buncha idiots.

Sea-going vessels don’t have restrictions on commercial use. Conveyances do. So, take your conveyance down to the boat ramp, position at least one wheel in the water to demonstrate it is a water-going vessel. Remove the “conveyance” placard, affix a “vessel” placard, and you now have a self-portaging vessel, free of the encumberences upon land vehicles and conveyances.