I went to Lowes the other day and bought some Aluminum flashing (for roofs), very bendable. It was a 10' x 14" roll. I made a shield around my filter and it held up pretty good. The stuff didn't get hot at all today when I was driving around town. I may sandwich some insulation in between two pieces of the flashing to make it even better.
My only question is that if you don't make a perfectly sealed box around the filter, won't the filter just grab air from under the hood instead of getting outside air?
