Just cut the flares along your door lines... Or track down some pre-cut Lexus IS flares. Problem solved. Retaining the back seat ftw.
On another note, this happened:
Backing plates came raw, so waiting on paint to dry to install lower legs, hardware for belt towers to install those, and ability to jack up rear for rear legs.
Took longer to remove the style bar to install a bar that's caused everyone major fitment and installation issues. I have about three hours in the whole project so far, two on the stupid style bar.