As promised I sewed the last four seams yesterday. Everything fit perfectly, no trimming needed. I did a row of staystitching around the outside perimeter to keep seam ends from popping. It is 54" x 66" right now.
Then I experimented with borders. I have lots of pieces that are lengthwise grain and are leftover from either backings or from border fabric from another quilt. What if I did a scrappy 8" wide border? I will be looking for more of the pieces today while I contemplate this.