Interesting--but why is it upside down? I'd be worried about breaking the board.
I'd flip it over, then rip a 1x1x6(?) strip and put it at the very end. You would feel the car ride up on the first 2x, then ride up on the second 2x, then when you feel it hit the third--stop.
I'd flip it over, then rip a 1x1x6(?) strip and put it at the very end. You would feel the car ride up on the first 2x, then ride up on the second 2x, then when you feel it hit the third--stop.