Really surprised that a trailer that is purchased new doesn't come with a VIN. Here in WA state the inspection for a homemade trailer is a complete joke, just a money grab. When I finished mine I showed up to the State Patrol at the appointment I had to wait 6 weeks for and all i had to provide was a weight slip from a state certified scale (gravel pit up the road) and the receipts for the materials used to build it. I provided receipts for the wheels, tires, axle and the steel. The guy literally didn't even look at the trailer, didn't test the lights, didn't comment on the lock'n'roll coupler (which usually catches attention because it looks weird) or anything. He stamped a VIN onto the tongue, riveted a plate onto the tongue with the VIN on it and sent me on my way, 10 min total. I went to the DMV, paid a pile of taxes and left with a plate. Whole process including driving between locations was under an hour. Other than waiting 6 weeks it was a piece of cake.