If you're carrying a lot of weight and you have the springs in the rear (not the airbag setup), maybe a set of Airlift airbags to bring it back up to correct ride height and level out the panhard will make enough difference to offset it.I am at stock ride height, slightly lower since I have too much weight in the rear. Panhard bar is new OEM.
Will learn to live with this over time, but for now it will drive me crazy.
Also, when you've had it aligned, did you do it with all your stuff in it, or was it done with the vehicle empty?
I carry a ton of crap in my 80 all the time and I know it affects how it steers. I'm guessing a 100 may be a little more sensitive to this due to the IFS.