I still had time before Linda came home, so I started work on the grill block/air dam. I taped an individual sheet of coroplast in place, measured how long I wanted it, and got to cutting.
I taped all the edges really well with my heavy duty duct tape prior to painting, and I got to use the license plate as a giant washer since I put two screws through the bottom of it near my new (smaller) air intake. I'm going to trim it tomorrow to match the bumper lines, remove it, re-tape the top, and re-paint it. I'm really pleased with the outcome.