If my search is well done, there are for now 11 "2-wheeled tractors with trailer" in the IMCDb:
http://www.imcdb.org/vehicle.php?id=82151#VehicleDetails
http://www.imcdb.org/vehicle.php?id=127926#VehicleDetails
http://www.imcdb.org/vehicle.php?id=475838#VehicleDetails
http://www.imcdb.org/vehicle.php?id=491318#VehicleDetails
http://www.imcdb.org/vehicle.php?id=528382#VehicleDetails
http://www.imcdb.org/vehicle.php?id=533378#VehicleDetails
http://www.imcdb.org/vehicle.php?id=622290#VehicleDetails
http://www.imcdb.org/vehicle.php?id=762661#VehicleDetails
http://www.imcdb.org/vehicle.php?id=789311#VehicleDetails
http://www.imcdb.org/vehicle.php?id=929804#VehicleDetails
http://www.imcdb.org/vehicle.php?id=1030282#VehicleDetails
And a possible 12th:
http://www.imcdb.org/vehicle.php?id=430425#VehicleDetails

There's one used by the main characters in a (very) short scene in the series I'm "working" on, so, as these vehicles are apparently used all over the world:
- do we give these vehicles a page, when with a role (other than background vehicle),
- related question: should we then have a specific class for them, as setting a generic "farming vehicles" implies to search them into 172 pages of "normal" tractors (ok, only 2 when one knows that they are identified as "Custom made" in the IMCDb. But who really knows that?),
- or do we just keep them in comment of the movie/series page, as, if they're self-propelled, they usually don't have a seat for a driver when without a trailer?