(a) A person may not operate a truck, road tractor, or truck tractor when another person occupies a trailer or semitrailer being drawn by the truck, road tractor, or truck tractor.
(b) It is a defense to prosecution under this section that:
(1) the person was operating or towing the vehicle:
(A) in a parade or in an emergency;
(B) to transport farmworkers from one field to another field on a farm-to-market road, ranch-to-market road, or county road outside a municipality; or
(C) in a hayride permitted by the governing body of or a law enforcement agency of each county or municipality in which the hayride will occur;
(2) the person operating or towing the vehicle did not know that another person occupied the trailer or semitrailer; or
(3) the person occupying the trailer or semitrailer was in a part of the trailer or semitrailer designed for human habitation.
(c) An offense under this section is a Class B misdemeanor.