You’re the third person to mention that, so I guess I should look into it
I can attest that it is in fact a legal alternative.
Basically, most states require that you register your motor vehicle in the state you reside (typically within 30 days of purchase or moving to a state). A "company car" can be registered in the state the "company" resides (but it can be operated in any state). Bonus if it's a "mobile office" (write off your truck for tax purposes).
Setting up an LLC is pretty straight forward (you can find the required paperwork and walk throughs online), You start with a name, a Federal Tax ID, and your documents/articles of incorporation. Simple to do by yourself and typically costs less than a hundred dollars for the entire process.
Some states require a "sponsor" (a resident who lives there) to vouch for you. The specifics can vary state-to-state but it's really easy to set up. It can also help to have a physical mailing address in that state, but not always required.
As I said, when you insure the truck, be certain to add the LLC as "also insured" (usually no cost to do so).
Also note that some states will require an annual inspection to renew the plates, etc (a consideration unless you don't mind an annual road trip to that state).
In some states, an LLC/ "business" can become a "hobby" if it's not generating income. That removes a lot of the corporate reporting aspects for taxes, etc.
There are also liability advantages to having the truck owned by a LLC/corporation.
Honestly, it can be a better (and legal) alternative than simply registering a vehicle in another state. I'm in Texas and that would actually be illegal in my case (if you live in Texas, you must register your personal vehicles here within 30 days). But a "company car" can legally be registered in the state where the company resides. YOU don't have to live there.