I decided to rip out the shoulder error even though it was only one extra stitch. I knew leaving the error was going to bug me and it didn't take much time to correct. That's done now and I also finished up the front pieces last night.
I've done a few little things along the way that were not included in the Rogue pattern. I think the changes will make the finishing neater. After the short rows for the shoulder shaping I left those stitches "live" rather than casting them off. I then used a three needle bind off to join the front and back shoulders. I also left the back neck stitches "live", rather than bind them off, and when it came to the directions to "pick up stitches along back neck" I simply slid them off the stitch holder and back onto the needles (decreasing in three places). Ta-da! No back neck seam.