Finished sanding and edging the canopy:
1. Used 80-grit sandpaper on a block-sander to finally get the forward edge of the canopy into shape. (It had two small irregular divots that are now essentially gone.) This process took a couple of hours and perhaps 10,000 sanding strokes. Ouch.
2. Radiused the forward-lower corner of the canopy.
3. Sanded the lower edges of the canopy with 80-grit.
4. Final-sanded all the edges with 400-grit sandpaper on a block.
5. Used the plexi scraper to finish off the edges.