That said, 26,000 is a common dividing line between "Personal" vehicles and "Commercial" types.
It's not the weight (many DP's are over 26,000 GVWR) that makes it a commercial vehicle. It's whether if you are carrying passangers or cargo for hire that tosses you into the commercial catagory.
And being over 26,000 gvwr doesn't require that you get a CDL. Again, that's a cash for hire thing. You just need to get the appropriate class of licence for your State,
According to the TDOT (the original poster's state) those who operate a vehicle Above 26,000 lb GVWR or GCWR (while towing > 10,000 lb) requires non-commercial Class A or B