Looks like homemade to me. Take my opinion with a grain of salt, but the Wisconsin Statutes 341.268 that are referenced in jontallon's DOT link have this:
They only mention that the body and frame are not originating from or resembling any previously manufactured vehicle. 818 should fall within that description.(b) "Homemade vehicle" means any of the following:
1. A motor vehicle that has been constructed or assembled from new or used parts or both using a body and frame not originating from and not resembling any previously manufactured motor vehicle.
2. A motorcycle that is a reproduction of a vehicle originally made by another manufacturer and that consists of a reproduction body that is combined with a new, used, or replica frame and drivetrain.