OP is right at 15% tongue weight should be towing great.
I don't use my friction bars anymore. 9 or 10,000 pounds and a sliding bar that slides on friction surgace. Percentage wise probably apply more friction when filing your finger nails. Mine is stock sway bar with air bags but only fill bags to level truck. And very cheap hitch. If getting that much movement search here for propride or Hensley. When your towing something with more weight than tow vehicle, when something does move trailer, ya tow vehicle going to move a little also. Just my opinion.