I have the 19" wheels not shore on the offsets of each. But they where difficult to fit. I have had to add a little more camber roll my arches and machine 3mm off the mounting face of the wheel. That said they look bloody great on now. Many people just run 4 fronts and that works. If you got the 19" i may possibly swap my fronts for your rears as i have a crazy plan to run a squire set up.
It has been done BRC on hear has them. I am not sure if he is running a staggered or square set up? Of if the 18s may just fit with running the right size tyres probable best to send him a PM and ask.