Builders of full size street bikes, dirt bikes, and even trailers builders are rapidly losing their ability to operate loosely and make "homemade" vehicles, trailers, etc. In particular the state governments and/or limiting and phasing out the whole "homemade" vehicle system where people could obtain a state issued VIN number for their homemade hot rod, chopper, trike, trailer, etc.
Additionally the state DMV's are starting to refuse to register vehicles that do NOT have EPA labeling. Some states even blacklist such motorcycles, bikes, trikes, etc so that they may never be registered. Environmental laws are in a growth mode.
If you want to get legal as a bike builder, trailer manufacturer, etc. I can do this for you. E-mail me -- Chuck Bauman -- at firstname.lastname@example.org or call me 602-540-8915.
Motorcycle Manufacturing Licensing Resource Page
Motorcycle Manufacturing VIN numbers
EPA information for licensed motorcycle manufacturers
Chopper builders information for becoming licensed motorcycle manufacturers
Bike builders information for licensing to become official motorcycle manufacturers