I fold and wad my sandwiched quilts up all the time and don't iron them. I think it might make a difference on how you plan to quilt them. Since I quilt in sections the only thing I care about is the section where I'm working and that can usually just be smoothed out with my hands. I guess I don't understand why a whole quilt that's been sandwiched has to be wrinkle free. I glue baste so not every inch of surface is attached to the other like in spray basting. If I'm making donation quilts I often will glue baste several at one time when I have big tables available and then after they dry, fold and store them until I can get them quilted.