Do it vertically instead of horizontally,so the dolls would be falling through,the final platform would be the victory trigger.
The best way to do this would be to have a moving floor rather than moving obstacles. You can tweak the gravity so the movement of the floor isn't felt by the players.
Ok, so I just started making this and already ran into problems. The only way I can think of that will allow the wall to move smoothly to the player is on a no-friction platform, but the only way the player can balance or stay on the ground is if the ground has friction. So this problem was easy to fix, I just added a non-friction platform 0.01 height above the friction one, however when the wall reaches the "Friction-zone" it flips over