By the time you have called in “expert witnesses” to justify your position, all bets are off. Good luck trying to show you were or were not "within spec." Add to this other factors like quality of brake shoes on the TT and TV, the stability of your particular towing combo or how well balanced your TT load was front to back and side to side and you will discover; that is what your lawyer is for.
Most people just want to know how well their TV matches their TT. Several will find that they are probably at or a bit over the limit, based on their best guess.
Even the so called experts hedge their numbers. Ford’s tongue weight data indicates a 10 % of TT weight others say 12 or 13%. Some claim WD hitches transfer 15% others as much as 22% of the tongue weight to the trailer.
Even if you weigh your rig on the scales you can easily get a 200 lb. shift due to TV gas tank level and TT water and other changing loads.
In the end, people have to be within their comfort zone, and we know that comfort zones vary quite a bit.