RotoZip and a belt sander
Hi Randy,
I, too, went the RotoZip method and am quite pleased with its ease of use. I used the right-angle attachment with the metal cutting disc (similar to what Van's gives you in the finish kit). Unfortunately, the Van's cutting disc does not fit the arbor of the RotoZip. I dialed in a speed of ~2400 RPM giving me a disc speed of about 1200 RPM (the attachment has a 2:1 reduction ratio or there abouts) and that seemed to do pretty well (not to much power to go crazy with and enough power to gently cut my way through without binding).
When I got my cuts pretty close with the RotoZip, I then used a 4" belt sander with 80 grit to smooth the edges down to exactly where I wanted. Straight lines and smooth curves were pretty easy to do. I then finished the edges with 180 grit and a rubber sanding block and then beveled the edges.
Other plans that I have for the RotoZip are to cut some of my panel and sub-panel cut-outs (the square/rectangular ones, at least) using the jig-saw attachment.
Oh, and consider a full-body poly-propylene painters suit (<$10). The suit breathes so it's not too hot. The little plastic shavings stick to everything!
Practice on the far edges of the canopy to get a good feel of how things will work out.
Take care and good luck,