..."Geez, how many pins does this take?"...As many as you want. I nearly emptied the box on my last UQ project. With a little experience, I was able to stop pinning roll hems. Now I get by with a mark (soft silver pencil) every 8" and just roll the hem as I go.
If I understand correctly, you stitched up the end channels in a "W" shape. Sweet! I've thought about doing that to match my preferred "pull" on a whipped end hammock.
Let us know how it worked when you get a chance to hang it...and of course more pics.