No.
GVWR is the TRUCKS total carrying capacity. Has very little to nothing to do with trailer towing ability. And I've never seen a law about how much trailer you can/should tow (other than CDL stuff).
Trailer sellers shade the truth (ok, lie) all the time - and most folks haven't a clue about towing capacity.
What you need to know is your tow vehicls GCWR - gross COMBINED weight rating.
You can get an F350 that is 27k lbs...the typical F150 is more like 14,000, SUV's (expedition say) is more like 12,500.
From that deduct the ACTUAL weight of the truck - in my silverdo's case it was 5700 lbs empty, 14,400 GCWR - so in REALITY I could tow 8700 lbs - NOT the 9600 lbs the book said!
The truck has a GVWR of 7000 - so total payload is only 1300 - my windstar had a higher payload capicity!
Not add 750lb toung weight to the truck and i'm left with 550 lbs of payload - people, cargo, etc, in the truck. WAY easy to be over loaded (4 door truck can hold 6 people..with a bumper pull trailer the bed is empty...you see camper folks with bikes, grilles, firewood in there, 4 or 5 people and a dog up front... or a cap on the back taking up evem more payload).
I now have an F350, haven't had it on the scales, but it's GVWR is 10,500. It's a 2 door, so 5700lbs is a guess - I can load it with over 2 TONS of payload! I've pulled the same trailer - NO comparison in how it rides/handles and stops compared to the lighter truck. Similar engines too. A diesel just makes things so much nicer yet.
Haven't done a fifth wheel but the truck is equipped.
From my readings the guy was breaking the law in the first place. There have been several threads on here about that it is illegal to tow an EMPTY 14K trailer behind a truck with a 11,200 gvwr.
So if I've a truck with a tow rating GVWR of 7,000 lbs is it illegal to tow an empty trailer weighing only 2,000 but it has a GVWR of 10,000?