Just my two cents here.

I formed a Montana LLC to avoid DC's 8 percent excise tax. We travel all over North America in a coach with Montana plates and tow a car with DC plates. We've had no problems at international borders or in rest stops patrolled by state police. I'm thinking that we're OK whenever we travel outside our home state. With probable cause, Texas or Colorado or Connecticut can check the registrations and insurance policies on our vehicles but they cannot legally levy fines or collect taxes on behalf of another state.

Apropos of best tax havens. Alaska, hands down. No personal income tax, no sales tax in most jurisdictions, forgiveness of property taxes once you turn 65. Best of all, an annual check for permanent residents from the state's oil and gas royalties.