UPDATE: You May Need A Commercial Driver's License - GoHorseShow.com
The above are links to the CDL sites, explaining the requirements you need to drive if your GRVW is over certain limit.
If you train, you are a commercial hauler if you are competing for any type of prize, even if your own horses.
While this won't apply to most of us, if you show, or even if you have a 1 ton dually, it can impact you, as most of the newer duallies are over the weight limit.
A trainer friend of mine, got stopped on way to Tom Powers. She has 6 horse, one ton and was on Highway 18, at 6 am when sheriff pulled her over. She got 9 citations, (only ticketed her for 2) and had to sit by side of road for 2 hours as well with loaded trailer.
And when she went back to sheriff car? He had her pulled up on computer, as in any place her name was mentioned as a trainer or winning? And wanted to know how she was going to ride 6 horses at a show??? And when she said 2 were just going to be exposed to showing, he wanted to know why she was doing that?
She now is legal, but took money and time and worry to get there.
According to requirements you also have to have logbooks, medical card, DOT # on truck, flares, fire extinguisher, forms for mileage crossing state lines, # for fuel purposes/taxes, do inspections and such.
Health papers and Coggins are being checked, and would not be surprised to see them start checking registration papers to see if name of owner on that is same as what is on Coggins, most barns get their Coggins pulled in barn/trainer name for the ease of it. But that may be coming to an end.
And DOT can and will declare you "Out of Service" too, which means you don't move until they say you can. Not good with live horses on.
Something to consider, and more money out of our pockets.