The NAFTA treaty currently gives trucks with Mexican registry freedom to operate in any part of the US virtually exempt from all NHTSA regulations and not subject to mechanical, safety, registration, operating hour limits, or loading limits imposed on US operators. Trucks with Mexican registry are not generally subject to any of the inspections by local, state, and federal inspectors to whom domestic operators must submit.

I think Richards suggestion is a "done deal" in many cases, regardless of whether California is allowed (or forced) to secede.

I suspect that the commonly held opinion (by US drivers) that 30% of the trucks and 80% of trailers operating under Mexican registry are stolen in the US may be a slight overestimate, but have been informed, by name, of at least a half-dozen who say they've seen their own stolen rigs operating in the US under Mexican registry and have been told that there's nothing that can be done (by US authorities) about it¹, because the treaty exempts them from inspection in the US.

¹ (They can go to Mexico and try to steal it back, but gringos in Mexican jails don't fare well.)

John