In theory you can use the backing, but in real life there is still al little of the sticky that gets on your iron. I have a big fiberglass sheet, and can usually fold it over, so BOTH sides are protected. If that does not work, sheet to small, ect, you can use parchment paper as a pressing sheet. It will not stick to that.
When you are stitching it down, remember, go with the pieces that are farthest from you, then the middle area and so on. That way it will not look like it was stitched "by accident".