Thank you Ron for taking the time to explain this in such detail.
Even with an engineering degree (not mechanical) it's still a lot of info. to wrap one's head around. Enlightening when you start to get a grasp on it. DW doesn't understand all the fuss.
I struggled with setup of our new Reese DC last spring and spent many hours re-adjusting and making numerous passes through the scale. I eventually figured out that the bars were too undersized and could not transfer enough weight to the steer axle. I had the bars wound up so tight I almost needed a gorilla to help. Moral of story - not a good idea to buy spring bars before you actually own the TT and just use the factory listed tongue weight...
Otherwise maybe just accept it all as magic, or take it for granted that the authorities and manufacturers have taken care of it all for you.