Mechanic at Hyundai says the right rear wheel of my 2012 Equus can no longer be aligned, as the alignment screw is maxed out. What will it take to fix this?

What is your question?

The right rear wheel is way out of alignment. While strongly accellerating or driving uphill (when more weight than normal is on the rear wheels) or hard cornering to the left, it sets up a strong vibration/shimmy in the steering wheel. The steering also pulls to the right when that happens. I recently had to have both front control arms replaced because the bushings were cracked and broken, something that should not be necessary after 53k miles normal driving. I'm afraid this repair will become necessary again if I leave this problem unfixed. What parts have to be replaced to enable aligning of the right rear wheel again, and how much will the repair cost?

What makes this problem better or worse?

Strong accelleration or driving uphill; also, it's worse when the car is cold

How long has your 2012 Hyundai Equus had this problem?

Since purchasing the car in December 2017