I can't speak for the rest of the world, but in Illinois, USA there is a B-Class Truck class. (Maybe call it alternate truck, so it's not Ill specific?)
The Alt-Truck class is primarily used for things like pickups that are used like pickup trucks that want to carry over XX load...
I admit I haven't researched this within the last 10 years, but as an example...
A regular truck is banned from some side-roads, but a alt-truck wouldn't be IF the destination is within the no-truck zone, while regular trucks would be. (Im ignoring the subject of moving trucks due to questions of the legality of moving a truck into a non-truck zone to avoid having to hand cary a house's furniture...)
As an example, from what I understand, a pickup with a alt-truck plate would be forbidden on driving on Lake Shore Drive in Chicago, IL, or Storrow Drive, in Boston, MA, it would be allowed on the side-streets.
So for a practical matter, I'd tie it into "Major Road" setting, and if forbidden there, forbid it across the board. If it's just tied into a street, allow the alt-truck to drive there.
a.k.a. Doug Krick