Well this is a pretty nifty idea!
So neat and tidy. It's always a bit tricky to achieve a nice, flat doll dress closure, especially when the item of doll clothing is small. I have also tried extra thin Velcro, snaps, buttons, and ribbon ties - whatever works and looks nice!
My choice of doll dress closures usually depends on who will be dressing the doll (older children and adults or young children) and on how much (if any) the back of the dress overlaps. In this picture, I made a big Matilda bunny. I used Flopsy's summer top pattern to make Matilda a dress. Since Flopsy has a rounder tummy than Matilda, the dress is wider and I was able to place rectangles of Velcro in the overlap area instead of butting them up. I sewed a decorative bow on top. (I knew the young girl receiving the doll would not be able to handle ribbon ties, buttons, or snaps so this was an easy solution.)
For a quick and easy, thin fastener, use low profile stick-on fasteners! I LOVE these. Cut the shape to fit and place where you want them. Leave them on overnight to adhere to the fabric before using.