Getting back to your original post:
"so I'd like some answers that will explain what I'm experiencing and why"
IMHO: You have gotten your wish. Clearly you are maxed out in every direction. Your half ton truck, with P's was never intended to haul a 30 something foot nearly 8,000# TT, period. Your payload (or lack thereof) severely restricts what most folks take for merely normal loading.
Can you do it? Sure you can but staying on the flat and not driving far or in high winds becomes more than a little bit limiting and not doing so invites problems. I have no doubt that everyone here wishes you nothing but the best but band aid solutions are not your friend.
Keeping in mind that when you get free advice (like this), you get what you paid for....
Good luck.
:C