You'd either need to thread the rope through some kind of guides that would make it follow the contour of the track (which would almost certainly introduce vast friction losses in the force on the rope), or else the force on your rope if you just let it go freely through the air is going to be at vastly the wrong vector for efficient pulling of the sled as it goes over the secondary rises. I suspect you'd find that it becomes unfeasibly hard to pull the sled over the second rises via a rope that is pulled from the top of the primary tower.