Re Stiffen the fabric:
I Always Use a fabric stiffener to prepare the fabric before embroidery or decorative stitching. (Unless it’s not a washable!)
I consider this a temporary, but necessary stabilizer!
Heavy Spray Starch
Odif (a new to me spray-on stiffener)
Gloop=Dissolve scraps of water soluble stabilizer in water
Also, “Best Press” is not adequate for this purpose