I was waiting for the cold weather to get here to do this. (Ninja Edit - Coroplast was from "recycled" campaign signage.)
Hopefully be able to leave a complete grill block on all through winter. I used a combination of Liquid Nails, Silicon Caulk, and Zip-Ties for attatchment. Liquid nails to hold the blue foam in place. Silicon for sealing where the Coroplast meets the bumper as well as sealing up the corrugation on the Coroplast so that no debris (water, salt, dirt etc.) gets into the hollow inside of the corrugation. Zip-Ties for holding everything in place while the liquid nails and silicon dried.
Removed front corner lights. Removed the front turn signal markers.
I skipped some pictures of the general removal of the bumper but did have this picture. Red arrows indicate bumper screw, and white arrows indicate hood latch mechanism screws (locations are approximate)
The space that was being blocked was a bit time consuming to get the proper blocking for because I wanted a flush mounted grill block rather than a recessed pocket that would create more drag. The bumper also has a curve to it horizontally so that had to be accounted for as well and the vertical differences in the depth of the bumper.
I used blue insulation foam to space the Coroplast so that it would be flush on the front.
From the back :
This the the middle where I will cut out some of the Coroplast if I encounter any overheating issues. Used a heated up coat hanger (soldering gun would work too but I don't have one) to poke nice clean holes in the Coroplast for the Zip-Ties rather that poke with a knife.
Used silicon caulking all the way around as well as on these corner "wedges" to hold them in place.
I did my best to get both corner wedges the same size but that didn't quite work out.
The final piece installed. Clear caulked around the zipties.
Before (best picture of my personal car I could find) :
Any comments / questions welcomed.