Here's a photo of one of the boot rings I bent yesterday in the wrong spot. You can see the edges are misaligned by nearly 1/8 inch. Grr. Well, nothing to do but start over.

This time I decided to take a different approach by cutting them somewhat extra large, and making the bend as the first operation. Then I drilled them to the floor panel, drilled the corners of the cutout, and cut out the center with the die grinder again.

I was able to keep the ring clecoed to the floor panel when filing the inside cutout. Using this order of operations was tedious and time consuming, but they came out great.