Pam, that pieced border looks great! I would add the extra blue border too.
I've finished the first pieced border for my 5 block version, plus a mitered narrow border in between to make it fit. I miter my borders before sewing them to the quilt. You have to cut exact, pin, and sew with an open toe and even feed foot so the fabric doesn't creep. I've been doing this for several years now. I did it first on attic window blocks and it worked so well I started doing it on full borders too. The cutting can be confusing at first. Just add the unfinished width or length of the quilt center to twice the finished width of the border. Be sure to leave 1/4" unsewn at the inside of the miter, pin and sew 2 opposite sides first, then pin and sew the remaining sides, sewing on the border side so you can see where to start and stop.