if you mean this spacer if i remember correctly, i used them because the wing was actually a little thicker on that side and it needed those to get the rod holes on the phenolic hinge to line up with the plastic ones glued on to the wing. if looking at the wing inverted like the pic, the hinges need to drop lower to line up. you could either sand the inside skin down or do what i did the plywood under the hinges.
I also sanded down on an angle the edge of the doors to get better clearance from the wing.