I found my home state required a physical address to register a vehicle, PO boxes weren't acceptable.
Years ago I worked for a regional office that covered 4 northwestern states. The laws varied, but we often had trouble with the law when working outside our resident state. The key word here was working, never had any problem when vacationing.
Once, when I lived in Oregon, got stopped in Idaho. Oregon didn't require a license on utility trailers. I had two motorcycles with plates showing, and the plate on the camper was visible. Was stopped for no license on the trailer. The deputy hadn't noticed the three visible plates.
My job required frequent moving, so I had a TT I lived in at work. When I went in the Army I put the TT in storage. I was assigned to Georgia, and eventually bought a car there. While I was gone my parents moved to California and took my trailer with them. After discharge I was headed home and was stopped at a CHP checkpoint. An officer walked up from behind, glanced at the California plate on the trailer, did a double take at the Georgia plate on the car, and when he saw my Oregon driver's license he simply called back "Hey Sarge, your'e going to want to see this!"
