Rocker panel NACA ducts are a no-no. There was talk of some people putting them in the rear corner windows too, but then you'd have to cut a 3" hole in the body somewhere to get that air to the wheel wells.

For ITS, I'm not real sure that cooling of the rear brakes is necessary. Yes it will make things last a little longer, but I don't think it's necessary to reliably finish a race..