Should have posted this already. I found two solutions - one short term and one long term
The V6 takes the 17" wheels no problem. However, the 18" wheels that I installed need to have the brakes upgraded with the V6 Brake Upgrade package from Ford Racing Parts. This is not a bad thing to do anyway, as it upgrades the V6 11.5" front rotors to the GT 12.4" rotors. It's 159.00 for the kit (handles both sides).
The other, cheaper immediate solution was to install a thin spacer and viola - no rubbing. I'm not sure if using the spacer has any long term effects, so I'll end up doing the upgrade, but at least for now I can put my wheels back on the street.