As I was crocheting one more of these to double check the pattern, I had an a-ha moment--or maybe an oh-no moment of “not one more color change.” So I modified on the fly.

After completing the last Main Color Row I just kept going, working the 5-dc shell all around the edge, placing them where they would appear in the staggered pattern. Then I found the ribbon. I almost called it “Prize Pony.”