If the problem is on the inside you could use spacers. If it is on the outside then trimming the inside lip on the fender is needed. If all else fails then just jack it up like a 4x4.
The next option would be to limit the turning by building up the stops on the axles. Don't go too far though, tape on small amounts and check it until it stops rubbing then go for a short spin. When you can handle the loss of turning radius and still not rub, you got it. Then epoxy the spacers in place. DO NOT weld them on. Just clean the surface good first and make note of the size so if you do lose one it can be replaced easily.