Love you tablerunner! You don't have to put batting in it if you don't want to. I love Hobbs 80/20 fusible quilt batt in my tablerunners and placemats. I did the same pattern that you used but ironed a full backing piece to the back of my batt. I then ironed the square centered in the middle. I attached the strips in the sew and flip method (ironing out each strip) thereby quilting it to the back as I went. When it was finished, I trimmed the whole tablerunner edge and added binding.