Haha! I do like the Kamm-back idea, you're one resourceful chap
Of course, I think that a smoother angle would be much more effective, however, your simple idea may allow a small amount of flow re-attachment. Also, it should go some way to reducing flow spilling onto the spare, so you may well see and/or feel some improvements. A-B-A tests will be necessary for hard evidence, so get that MPGuino calibrated
All in all, a great little project you have there. Keep up the good work.