I used a dowel once, with the contour of the riser shaped in into the dowel. I used double sticky foam tape to attach dowel to the riser. The rubber band was attached at the "back side" of the riser end of the dowel.The rubber band was then streched over the arrow to the dowel on the "belly side" of the dowel.
It isn't clear to me how the rubber band comes off the arrow while drawing the arrow on your set up. I do like the simplicty of the holder though.