3rd time is a charm! I used a different material for my second attempt and did not like how flexible it was. I watched it blow backwards in the wind on my ride home this morning. For my third attempt, I used the heavier material and added one more inch past attempt two. I still would have liked it to be a tad wider but that is as wide as the material allows.

Attempt 1, 2 and 3:


Here you can see how floppy the 2nd one was:


The final product: