build a 30 degree shooting board using man made materials, to hang off the side of your bench, with the angle set by wedges that are a lot easier to make to a consistent and accurate angle. Plane runs on a reference surface sitting on your bench, the resultant angle is your 30 degrees. Plane the angled backing piece first, that gives you a reference to measure from, then the support can be screwed in place to give you a consistent width. Make a second one, to support the other end of the board (as some people do with shooting boards), or make the main one long enough that you can cut the support piece off the end. If the wedges are set back from the edge of the angled piece, then you have room for clamps if you need them.
Colin, Czech Rep.