OK, so this time I decided to see if I could zip tie the pan on. I wasn't sure if I would be able to do this because where I'm tying to is not very adjacent to the edge of the pan and more perpendicular. But I thought if I drilled holes equidistantly, I could hopefully pull the pan into place, center it up, and snug it to the wheel.
I drilled 3 holes and loosely attached the zip ties, then centered the pan, and gradually pulled the ties tight in rotation.
Once they were tight, the pan was fairly snug against the wheel...
But it was easy to flex the pan enough to get my fingers behind it. Air can get behind this and pull it out, but it was definitely more secure than with the velcro.
It looked pretty good, considering the pan had been run over, so I was ready for a drive to see if it would hold.
After 20 miles with speeds up to 60 MPH, the pan went off center a bit, but not enough to feel that the wheel was out of balance. There was a bit of a pull to one side, and a droning, but I think that was more due to the fact that I rotated the tires while I was doing this, and they're not worn into their new positions yet, and the wind was blowing pretty strongly.
This looks like it will work if I use more zip ties, and drill a hole for a valve stem extension. I'll just have to cut a bunch of ties if I get a flat, or when it's time to rotate again, but I like the way this looks, whether or not it gives me any aero advantage.