i'm running stock sedan fenders on my wagon. there's A LOT more room up front now for wider wheels. i don't want to run staggered offsets, so i'll probably wind up running a 15 or 20mm spacer up front with my current 18x8 +48 wheels. I have yet to roll/pull my rears though. I run 17x8 +48 for track/auto-x (STX width limit) with no spacers.
If you do roll/pull the rears, you should be able to fit 18x8.5 +45 all around, and still have room for a ~10mm spacer up front.