It would obviously not be recommended mate but I did mine last week and used the angle grinder to shave off about 5mm to clear the tyres. There is about an inch clearance between the edge of the plate and the spring. I tested mine on a yard full of pot holes before going on the road and have had no problems yet whatsoever (touchwood). Just make sure that there is plenty of rim left to hold the spring but because of the tension in the spring if the spring is over by the rim you have a problem anyway!!!!!!! Mine is great now and even with me, the missus and the two kids in the back I get no rubbing at all.
It's your decision and I cannot condone doing this but I could not wait until I got spacers but as I said before spacers would have pushed my tyres onto the arches. Let me know what you decide (out of curiosity) but remember the plates (and rim) are there for a reason.
Hope this helps Deano