If that's the case, there are A LOT of folks out there breaking the law!
It sounds like you are thinking of COMMERCIAL HAULERS.. Then, yes, commercial haulers are subject to those regulations..
If you are hauling your own personal stuff, you can and should be able to drive a full size Semi truck to tow your 5th wheel... You might still be limited to GCWR of #26,000 for the combo, but that's where it gets 'fuzzy'...
Good luck.
Mitch
2013 F150 XLT 4x4 SuperCab Max Tow Egoboost 3.73 gears #7700 GVWR #1920 payload. 2019 Rockwood Mini Lite 2511S.