I can't do a lower grill block,
I dont have a lower grill. The car got hit in the parking lot and they wanted too much to fix it, so I just amputated the bumper. Theres not much behind that coroplast really.
As for attachment methods, I tried the center bolt and I tried zip ties. Neither of which really worked well. And both of which I would have had to drill out 6 holes, 1 for the valve stems and 1 each for the lug nuts. It would have been too much work for something that I think would have looked worse. The only question now is how long the tape holds up.