Making a mess wet sanding the body filler skim coat:
Other than continuing to sand/fill surface imperfections, the last remaining hurdle is trimming the forward edge of each side and figuring out how I'm going to attach it to the hatch. I was thinking super sticky double-sided 3M trim adhesive tape (Daox's suggestion), but then I thought if I ever want to remove this without wrecking it, stainless screws might be best.
I'm going to be away this weekend (Hybridfest), so no more work until next week. But the Kammback will have its first road test in unfinished form on my way to the Ottawa airport tomorrow.