Here's the MN law pertaining to class D driver's license: c) Class D drivers' licenses are valid for:
(1) operating all farm trucks if the farm truck is:
(i) controlled and operated by a farmer, including operation by an immediate family member or an employee of the farmer;
(ii) used to transport agricultural products, farm machinery, or farm supplies, including hazardous materials, to or from a farm;
(iii) not used in the operations of a common or contract motor carrier as governed by Code of Federal Regulations, title 49, part 365; and
(iv) used within 150 miles of the farm;
(2) notwithstanding paragraph (b), operating an authorized emergency vehicle, as defined in section 169.011, subdivision 3, whether or not in excess of 26,000 pounds gross vehicle weight;
(3) operating a recreational vehicle as defined in section 168.002, subdivision 27, that is operated for personal use;
(4) operating all single-unit vehicles except vehicles with a gross vehicle weight of more than 26,000 pounds, vehicles designed to carry more than 15 passengers including the driver, and vehicles that carry hazardous materials;
(5) notwithstanding paragraph (d), operating a type A school bus or a multifunctional school activity bus without a school bus endorsement if:
(i) the bus has a gross vehicle weight of 10,000 pounds or less;
(ii) the bus is designed to transport 15 or fewer passengers, including the driver; and
(iii) the requirements of subdivision 2a are satisfied, as determined by the commissioner;
(6) operating any vehicle or combination of vehicles when operated by a licensed peace officer while on duty; and
(7) towing vehicles if:
(i) the towed vehicles have a gross vehicle weight of 10,000 pounds or less; or
(ii) the towed vehicles have a gross vehicle weight of more than 10,000 pounds and the combination of vehicles has a gross vehicle weight of 26,000 pounds or less.
So, just have them license the truck for under 26,000 lbs and you can drive it. But you will need a air brake cert.