I agree with Matt. Try the crossing thing and see how that goes. Can't hurt that's for sure.

You speak of the track bar to bring the rear axle back to center. I know mine is off about an inch maybe??? I wonder if the rear axle being off caused the tire to wear like so because of weight distribution? I know you carry a lot of stuff in the back so could the weight have more pressure on the inside part of the tire b/c the rear axle was shifted to one side some? Probably not....IDK.