I just went through this in Nevada. The requirements are below, but I am sure you already know them. The hardest part of the tests is the worrying about passing. They are really not that difficult. This is the way it was explained to me.
If you are towing a trailer more than 10,000 lbs gvrw ( that is a pretty light 5th wheel) you need at least a J endorsement. If that combination is over 26,001 lbs you need a Class A non commercial. It really makes no difference what your rigs actually weigh , it is the manufactures gvw figures that count. If the vehicle has air brakes you need the air brake endorsement. So since most of out HDT’s are at or over 26,000 lbs GVWR anyway you really cannot legally tow anything without a Class A with your truck.
For me I just did not want to worry about it and needed to get my Class A. I am very glad I did. If it was explained to me incorrectly I apologize for passing on the error.
Nevada Class A
May drive any combination of vehicles with a gross combination weight rating (GCWR) of 26,001 or more pounds, provided the vehicle being towed has a gross vehicle weight rating (GVWR) of more than 10,000 pounds; or
Any combination of vehicles not exceeding 70 feet in length with a gross combination weight rating of 26,000 pounds or less so long as the gross combination weight rating of the towed vehicles does not exceed the gross vehicle weight rating of the towing vehicle.
May drive any single vehicle with a gross vehicle weight rating of 26,001 or more pounds, or any vehicle which is towing another vehicle which does not have a gross vehicle weight rating of more than 10,000 pounds.
May drive any single vehicle or combination of vehicles, that does not meet the definition of a vehicle for which a Class A or B driver’s license is required. May tow a combination of vehicles not to exceed 70 feet in length and not to exceed a combined weight rating or a combined weight of more than 10,000 pounds without any additional testing or endorsements.
May tow a vehicle (GVWR) or a combination of vehicles (GCWR) of more than 10,000 pounds. The combination of vehicles may not exceed 70 feet in length or have a combined weight rating or a combined weight that exceeds 26,000 pounds. If the combination of the towing vehicle and the towed vehicle(s) exceed 26,000 lbs., a Class A license is required.