I would go with adjustable rear camber arms. I bought mine over on the MB forum, or you can make your own. I put the new arms on with centers at 12" and my tires are wearing perfectly even. Never had it on a rack.

Check here: https://www.crossfireforum.org/forum...r-cambers.html

Be sure the ends have rubber bushings, and not pivot joints as they usually end up noisy.