A lot of coilovers are slotted like this, including my KW's. It changes the kingpin, but I measured only 1.5* difference at the 'in' position versus the 'out'. Basically, however far you slot it, you'll get twice that distance as additional tire/coil clearance. You'll need 3-4 times that distance in travel on the strut top to compensate, though. My suggestion will work much better than spacers since you won't have to beat the fenders as much.

If fitting crazy wheels were easy, everyone would do it. Now get to work!