No one has resolved this issue, hence the thread and continued additions.
The Pirelli tires are a fine tire. There is debate about the General Grabber tires being crap and thus worth swapping off. It has also been suggested to change rim sizes to a smaller rim and larger tire sidewall to absorb more.
Or ultimately you get rid of the car and try something else - Going to a Tahoe/Yukon/Escalade is a popular decision, but one with its own risks as there are numerous reports of engine failure in the L87 V8 from GM, but thats another topic in itself.
I am going to take mine to an independent tire shop and have them road force balance my rims again... just to see how well Lincoln did it. If that doesn't do anything, then its back to the dealer for me and I'm going to push for them to inspect other areas of the car - motor mounts, drive shaft, etc. Anything that produces rotational inertia that could add in vibrations. I'm going to also request all adapts shocks to be inspected, and maybe a reset of the system in itself to see what that can do. Lincoln sells the Navigators ride as adaptive via camera (scans to road ahead and adjusts the dampening based on the scan)... perhaps there is an issue there.
I am fortunate to be in a position that I can allocate time to figure out what the FK is wrong with these 100k+ cars, but eventually I will run out of patience and get rid of the damn thing.