Brettski, you'd better check on skateboard elbow and knee pads the next time you're shopping e-bay. Those bones aren't getting any more flexible, and you'll really feel it whenever you bump that spot on your head. You don't want a 3-peat!
I'm sure you could fix up some railings for that plank if you tried. They might not hold you on, but they'll be a reminder what your boundaries are.