Well years back when we were TC users my trucks also had to pull heavy GN stock trailers...dot registered GN flatdeck trailers/GN/bumper pull enclosed trailers.....boat trailers.....haul hay.....deliver firewood.....normal farm and ranch stuff and loan them the kids/family because they didn't have a truck.
My trucks did and still do double and triple duties although we don't have a TC at this time.
Q#2...Having owned three different TC years ago I still look in on the TC forum to keep up with changes which are many. Most TC owners over here have a much better grasp of a trucks actual capabilities per mfg mechanical specs and understand how to find and read the vehicle mfg website sources that show the mechanical sameness or differences in each size truck.
JMO but the 5th wheel and TT forums have the most payload sticker weight cop types mainly because many are newbs and have never owned a truck before so they bit into the payload sticker or trucks gross weight minus gvwr = payload numbers.....and completely ignore the fact that the new higher gvwr payload sticker numbers, in many cases, will and has exceeded a tire/wheel load or rear suspension ratings.