I could see maybe spraying the back of the top and sitting it on the batt, then placing the backing fabric on top of the sandwich, with right sides together and sewing around but leaving a spot to turn. The spray bast would keep the top and batt connected while you turn it. You could then smooth it out and when you had it perfect, stick your arm in the hole and lightly spray the back fabric and then smooth it again. Is that what you mean? Let us know how it works out for you.