This type of thing is exactly why the federal government required states to pass uniform CDL laws 25 years ago. Before that, we had to comply with every state's licensing laws. Later states were taken away motor carrier regulating authority, as well as posting a fuel bond. In MO a class E license is required for a non CDL vehicle used in commerce. In Louisiana, a class E license is for a personal vehicle only. I hear of this type of thing with people who rent medium duty trucks. The rental company assures the renter that the vehicle is under 26001 gross and does not require a CDL, but the renters are not made aware of the crazy laws that some states have regarding non commercial vehicles as defined by the Federal Motor Carrier Safety Administration.
If the Terra Star did not have a RV body on it, you probably were required to conform to their dumb law.