Well heres what i did with my mount, my 285/75's were only just touching under full lock whilst driving normally and would rub pretty bad when 4wdriving.
I pretty much followed the first procedure Max posted up, as i didn't want to go as drastic as the others and wanted to try keep it as factory looking as possible.
It took me around an hour each side once the car was on stands and the wheels removed. I first marked off the area i wanted to cut, and threw some duct tape around the outline and over the bush (i didn't even remove the rubber bush, but would recomend it). I then cut the section out using a 4" grinder with a cut off wheel.
Using some scrap 2-3mm plate steel i had sitting around i cut it down to a rough rectangle size that i would weld in. I then shaped the metal with a hammer and the grinder in the vice so it sat flush against the cut edge of the mount. I then tacked it off keeping the top edge of the plate level with the top edge of the mount, then beat it more into shap using a hammer. FInally i welded it up, ground it smooth and then hit it with a coat of kill rust matt black.
Top View:
Side view - Full lock with tire:
Bottom View:
Side View - Full lock, compressed:
Side View - closest point, compressed (lifting rear wheel), sorry bout the leaf
It now clears the body mount heaps! but that also because i found a place that does a good wheel allignment too. I've had all 4 wheels off the ground and have not yet hit the body mount. The top of the guards are a different story though and still need a little bit more trimming.