In the United States, for instance, the Federal Motor Carrier Safety Administration (FMCSA) sets the standards for CDL requirements. As per the FMCSA regulations, a CDL is generally required for operating any vehicle that has a gross vehicle weight rating (GVWR) of 26,001 pounds or more, or any vehicle used to transport hazardous materials or passengers (beyond certain limits).
When it comes to towing a fifth wheel camper, the combined GVWR of the towing vehicle and the trailer must be considered to determine if a CDL is necessary. If the combined GVWR exceeds the specified limits, a non-CDL driver may not be legally allowed to operate the vehicle combination on public roads.
It's important to check the specific regulations and requirements in your country or region regarding CDL requirements for towing a fifth wheel camper with a tractor-trailer. If a CDL is required and you don't have the proper license, it's illegal and can lead to legal consequences, including fines and potential liability in case of an accident.