I did a grill block that sits up against the upper radiator and I leave all year round. I left the lower portion open. As soon as I figure out how to post the photos I will put them on the board with an explanation of what I did. I've had this setup thru all the seasons and temps that come thru Chicago with never a problem.

 

Here is what I did for my grill block. For the material I used for the grill block you can go to your local hardware store, I went to ACE, and look for the black plastic roll that is used for runners. It comes in a standard width, at least at my ACE it did, but have it cut to about 36in in length or more. For my '07 I cut the length down to 271/2 inches, your length may vary depending on your model year. When I pulled the top of the grill away I slipped the guard down and then after marking my holes and allowing space at the top of the guard, I used 6 plastic zip ties to attach it to the top of the radiator, again you may use more. I left the bottom open so as not to overheat the system by totally block it. When you get down under the bumper you will notice that there are a 3 radiators. I like the look, as it is nice and clean. I've used this throughout the year and the car never over heated in the summer.

Go to Photo Gallery and look for 07 grill block by me and you will see 19 photos.

 

This is what some of us have done:

They don't look as good as the Cloud Rider version. They are more expensive than cardboard, plastic or other. However, the velcro flaps allow one to easily cover and uncover the upper portion of the grille as desired. As for the lower portion, I started with cardboard over a portion of it and then moved into using 1/4 inch painted plywood. I did not cover all of the lower grille.

 

Billy, I've had similar versions on my pickups over the years, except wasn't quilted and had a zipper down the middle and snapped onto the front of the vehicle (after you drilled and screwed snaps to the sheet metal).

 

I'm in NW Nebraska right now, and in the middle of a sand storm that reminds me of 30's Dust Bowl film footage. We have 18" sand/silt drifts all over.

Another benefit of the grille block is, hardly any sand is getting in MY radiator!
Still not good for my paint!

 

WOW Lone Ranger! VERY in depth picture essay!! I think your method is better for the winter weather than the nice looking version I purchased. After installing mine I realized that it is still several inches from the radiator, and I'm sure the cold air gets there... along with the few slots it has in it. I may do a combination for the extreme cold months here in Detroit. That includes November this year! Brrrrr!