This is for horse owners, but it also points out that states can have "more stringent" regulations than the feds, but not less stringent:
How Federal Motor Carrier Safety Regulations Affect Horse Trailers.
How Federal Motor Carrier Safety Regulations Affect Horse Trailers.
In 1986, Congress passed the Federal Commercial Motor Vehicle Safety Act (FCMVSA/86). This law requires each State to meet the same minimum standards for commercial driver licensing. The states may have more stringent regulations of their own, but they may not lessen the standards.
*******************************
So the states are completely within their rights if they want to jam you up for a flat bed or different truck configuration. What surprised me is that all these people I know who haul their horses to shows *might* be considered to be engaging in "commerce" is they have the possibility of winning money at the show, especially if they travel out of state, but not necessarily required to follow the FMCSRs:
From the same page:
"`Commerce' can be more loosely defined as actually "involved in a commercial venture" or the "intent" to make a profit. This does not mean actually making a profit! Running a commercial stable, hauling horses for show (with intent to profit), race, sale, training, or for compensation are some examples of commercial enterprises. Prize money and showing to increase the value of the horse can be interpreted as profit. "
And this:
1. If you are driving a vehicle or combinations of vehicles under 10,001 lbs. GVWR or GCVWR, you don't have to be concerned with the FMCSR's or a commercial driver's license (CDL). You must, however, follow the safety equipment requirements and driver's license requirements of your own state.
2. If you are driving a vehicle or combination of vehicles interstate 10,001 to 26,000 pounds GVWR, you must decide if you are commercial and subject to FMCSR. You do not need a commercial driver's license (CDL), although your home state may have an additional classification of driver's license. (The initial decision is up to the owner whether or not he/she is pursuing a hobby or is involved in interstate commerce and he/she bears the burden of proof. If you only travel within your state, you may follow the state definitions of commercial, but if you plan to travel into other states and your vehicle or combination is 10,001 lbs or more, the official recommendation from Federal Authorities is that you follow FMCSR's)
3. If you are driving a vehicle or combination of vehicles intrastate 10,001 to 26,000 lbs GVWR, you must follow your home state requirements if they differ from the Federal requirements.
4. If you are driving a vehicle or combinations of vehicles 26,001 lbs. GVWR or more interstate you must have a commercial driver's license (CDL) and you must follow FMCSR.
5. If you are driving a vehicle or combination of vehicles 26,001 lbs. GVWR or more intrastate, you must follow your state guidelines for commercial licensing (CDL), and FMCSR requirements.
Although these days I wouldn't be surprised if some government yahoo would try to classify horse manure and the C02 they exhale as hazardous materials.
But it's for our own good, right?