The guys with the RV's don't have to have a CDL or even a medical card. Some of them are built on Class 7 & 8 chassis and use air brakes. In my area the DOT is cracking down on the Farm use stuff, they are pushing having a yearly DOT inspection on the equipment and if over 26,000 the drivers are required to have a CDL with a medical card. They do get a pass on registration fees for farm use.