Problem with Offset

I'm in the process of putting on 18x9,5 Y2K C5 rims with 65mm offset in the rear. I want to use hub centric wheel adapters to make them to fit right. Is there anyway I can use a 1" wheel spacer. The reason I ask is b/c I don't want the wheels to stick out of the rear fenders. Will I get away with this ? I calculate that would put my offset to 40mm. Would I have to get my fenders walls rolled in ?
Thanks
Alex

The ideal offset would be 50mm to 56mm. With that spacer putting the offset at a little under 40mm, it would be a VERY aggressive fitment. You would have to roll the fenders pretty hard.

Chris