Thank you for the advice. I will check this out in the morning.

Question—why did our 40’ GD Solitude trailer so well and this so poorly? The Solitude connected to the truck using the same hitch point, height etc.

Check To see if your F350 has a rear sway bar if not I would suggest a HELWIG rear bar also turn off sway control on your control panel. Those two things corrected my sway problem with our 2015 F350 single rear wheel. How I found this out is we had a 1999 F350 single rear wheel and our Montana towed perfect but the new 2015 was just terrible. Those two things will correct your problem when towing also each time you Start truck while towing you will need to scroll down and turn sway control off again. It’s a long explanation why sway control needs to be off but simply said the truck is in a constant battle while towing activating the rear brakes making the trailer sway worse. The truck computer is sort of in control. The Helwig rear bar if you install one use the center hole for your adjustment.