Passenger side: unscrew taps holding on the side skirt, this allows you to slide the coroplast in between the side skirt and body.
There is also a small opening for the jack point where you can thread the coroplast up to hold it in place while you are screwing it in.
Closing the gaps on the rear bumper:
Finished Product, Rear bumper:
Mid-car, showing exhaust clearance:
View from the front:
Observations: did a preliminary quick run through my usual test spot, got 54.6mpgs (my previous run with current aero mods minus the belly pan 51mpg).
will do a few more runs to get a more accurate reading. Oh, and the road noise has decreased immensely!