I ended up buying one of the called-for Weeks threads, "Pumpkin." It replaces the DMC 721 that I was using for the dark orange. In this square, it's used for the border. The difference is hard to see here, but the subtle shading makes it look less glaringly orange to me.
I'm enjoying the incremental approach to this pattern. It's nice to know when it will be done, and to know the ultimate finish can be accomplished via attainable monthly goals.
I got a sewing machine over Christmas, and just got it set up this past weekend. My first ever pillow-style finish: