(4) Operating a motor vehicle while allowing a person to ride:
- (i) On or within any vehicle, trailer or other mode of conveyance towed behind the motor vehicle unless specifically designed for carrying passengers while being towed; or
- (ii) On any exterior portion of the motor vehicle not designed or intended for the use of a passenger. This restriction does not apply to a person seated on the floor of a truck bed equipped with sides, unless prohibited by State law.