Began working on seam-matching the front and rear halves of one of the wheel pants:
1. Duct-taped the haves together. I noted that the aft half of the wheel pant had the straightest edge, by far. I decided it was good enough to use as a reference.
2. Located the widest gap between the two, which was a small area almost exactly1/4" wide.
3. Marked a line 1/4" forward from the edge of the aft piece, all along the perimeter. Separated the two halves.
4. Dremeled very close along the line.
5. Block-sanded the edge until it met the line exactly.
6. Duct-taped the halves together again.
7. Block-sanded the side of the seam to smooth the level of the joint.