Vehicle security for long road trip

Hagerty has a brochure... everyone has pretty much hit on the majority of points with the exception of covering the vehicle to make it less attractive (although that may draw attention so 6 of one - 1/2 dozen of the other). WeatherTech and others offer locking car covers. None of these things will stop a determined thief but might discourage an opportunist.

https://www.hagerty.com/assets/PDF/TheftPamphlet.pdf