Find out who does PROBLEM CASE alignments in your area. Or customization. You may find its the same guy. You might find some interesting vehicles at the shop, like low rider's and trucks with lift kits. All of those require special alignment settings.
If you stay with the typical shop, I'd try setting 0.5 degree castor difference between left and right side, right side with more castor. I'd also try adding some camber on the left side.