Bottom line is if one can get the tow vehicle and trailer level with the correct trailer balance, without a material amount of proposing or sway, and the components ( hitch, frame, suspension, tires, brakes, engine, transmission, axle, etc) are up to snuff for the loads then one will be fine. In fact if one does all that probably better than 75% of what I see on the road. The 7% trailer balance for a boat is a big differential on the impacts to droop and proposing. As opposed to the 500/5,000 recommendation for WD it would be more like 500/7,143 with a stock class 4 setup. Put on good tires, balance the trailer to 7% and then see if you can get the truck and trailer level. If so jump up and done on the trailer tonge and see how much it bounces (porpoising) and make sure it does no hit or rest on the bump stops (if is does in the driveway stopped with you jumping, it certainly will out on the road. If it is not level or it porpoises too much then bag the rear end and call it a day. That all has its limits though as the side wind profile gets bigger and the weight gets toward the top end limits additional equipment such as a WD or anti-sway hitch may be needed.
There are multiple physics principles at play. Understanding them to certain degree certainly helps make a decision and there are multiple sites that explain with diagrams. You however don't need to be an expert in live load, deflection, moment of inertia, fulcrum, etc to know that a severely unleveled or unbalanced trailer setup is going to be less than good at 60 mph or that a 35 foot camper is going to pull a half ton truck around when hit with high wind from the side.
Just remember that if you get into an accident that you may be at fault if outside of the rated/recommended limits which includes not using a WD hitch when recommended.