Have you accounted for the crown in the road? When I put tires in my 4Runner it always pulls toward the high point in the road. Typically to the left in the right lane and to the right in the left lane. The larger tires could be increasing the effect of the road crown. Just a thought.
I can't find it now, but I do remember seeing one, maybe two, other people with the same problem. I think you're right about it not being seated properly.
Have you checked the air pressure in the tire? IF the pressure has gone down since you winched it up the tire might have shrunk just a little. That might be enough to allow some movement.
Get the P/N from the Quadratec link and ask the parts person to see if it's available to order in their system. If not, give the Quadratec link to the service manager and ask them if they can order it there. If you haven't pissed them off too bad they might agree to that just to be done with it.
Use ramps, blocks, whatever, under all 4 wheels to give you the room you need, but make sure you set the parking brake and leave it in gear so it doesn't roll off on top of you!
https://www.shrockworks.com/JJT-SL-pr-16305.html
These are the preferred sliders for the 4Runner and Tacoma crowd I think. Shrockworks are high quality and very strong. They mount to the side and bottom of the frame.
Check out the part about towing in this article. It seems to indicate 4.10 will be available for the diesel.
https://www.drivingline.com/articles/jeep-gladiator-diesel-what-to-expect/
Did you get this information from Jeep? Mopar? There are lots of opinions on the forum but I haven't heard anyone cite a knowledgeable source. If you've acquired this info somewhere other than what someone posted on the forum, please let us know where it is.
Can you point me to your source for this statement? I've read elsewhere on this forum that the Rubicon shocks are actually better than the ones that come with the lift (and the lift springs lower the GVWR).