I tried something a bit different
The tape worked. The only problem was that I really didn't want an X going through the t-shirt designs. So I decided to give something a try: I took the backing and the flannel and sewed the X on them. Then I took the t-shirt block and on the wrong side, I squiggled Aleen's ok-to-wash-it, let it set up for 3 minutes, and pressed it on to the backing/flannel block. Since I put sashing around the t-shirts, I made sure I didn't get any glue on that. Now my t-shirts are sitting to dry and it worked like a charm!