I think this is a great dress! and I love your fabric, I've been dreaming of blk/red wide stripe as well. Will look on JA's! you might just practice with the steam-a seam, on small scraps. I use it on my knit hems, 1/2" width tape. I sort of push the fabric against itself as I apply the tape (I put it above and along the fold line, not below it, then fold the edge up, pushing a bit as well and trying to avoid letting the fabric stray from the 'straight' line). I've found that I can then use a long straight stitch on the right side to topstitch and finish. Pretty much gets out the wavys!