Thanks so much for the replies folks!
Using a reflective fabric seems like it might solve a few of the potential problems. A cut, hem, grommet, and zip tie approach might work with the right fabric. I fear it will get a bit pricey, but if its done right the cover should last at least a few years yeah?
Has anyone come across a highly reflective fabric paint that could be applied to canvas, or other canopying materials?
The way a plan morphs as the hive mind provides their advice is one of my favorite things about the eplaya. You guys rule.
Edit: Has anyone used reflective powder/beads either in paint or another way?http://www.colesafety.com/Reflective-Powder-Glass-Beads-GSB10Powder.htm?productId=77