I've been pulling trailers in Cal for decades everything from small boats to multi axles with Over-sized loads like the Aluminator....
and I've never been hassled, pulled over, or ticketed.
To be honest in all the road hours I have trailoring back and forth by myself and with friends... We're talking LA south to Shelter, Ensenada, Mulege, North up to Avila, Morro, and Monterrey Bay. I've never once been in a vehicle pulling a trailer that got pulled over harassed or ticketed, on the US side of the border.
PTI plates, keep to the right, the speed limit is 55 but as long as you stay under 65 and slow down when you see the CHP your fine.
Jim