Well, after doing some soul searching prompted by your many suggestions, it seems like the problem may be solved.
I made sure all the tires in both the TV and TT were up to spec pressure, I found a few miles of dry, level, smooth road with no traffic. Yes, we have some of those here in FL at this time of the year -- albeit cooler than usual.
First w/o the sway bar I got the rig up to 25 mph and performed, once again, the brake controller (P3) adjustment per mfr instructions. Ran the rig for many miles at the speeds where the problem had shown up and varying the road conditions from smooth to bumpy -- no problem. Repeated the same cycle with the sway bar on -- same results.
Even over bridges with quite bumpy approaches, I could not get a jerk out of the trailer. Unless something else shows up next, I believe I did not do a good job with the initial brake controller adjustment and there may have been some erratic signals being sent to the trailer brakes. I'm happy.
BTW, I'm making a habit of anticipating very tight turns, as well as when backing in and removing the sway bar link altogether.
Again, thank you all for your excellent insights.
2004 25' Safari
2010 4x4 Ford EB Expedition