Stumbling through the remains of the Bus Crash Scene, we arrive at Camp Knossos. Although the location is clearly a maintained property, the setting is considered less "bucolic" and more skewing toward "desolation," given the foreboding apparent absence of people around. A forced perspective roadway behind a barricade adds the malaise of isolation to this setting. The only living soul is a Scout who stands right by the remains of the bus crash who may startle the guest by announcing suddenly, "I think we made it!" or some other line appropriate to cue horrible things about to happen in a horror movie. It does indeed: he is then suddenly grabbed by the hair and yanked violently backward into the darkness.
This would be achieved like so:
Now, I'm no engineer and I don't have a workshop to mock up a prototype for this mechanism, so let me at least describe the performance specs for this device:
A form-fitting plate is attached by cantilevered pipes to a counterweighted swing arm that pivots within a track which allows the plate to slide backwards. A manner of catchment keeps the counterweight at the fully dropped position at the nadir of its arc which allows a mounted garage spring to extend when the ScareActor is pulled backwards; this facilitates the reset by providing energy to slide the person forward to where the center of gravity is more manageable by being closer to an area above the pivot point. The form-fitting plate incorporates a safety harness into an integrated costume with one pant leg (a sneaker sole actually is affixed beneath the horizontal part of the plate beneath the foot); this allows the other leg to flail free as the actor is launched backwards. Carefully positioned spotlighting and a darkened back of house area will help announce the actor and obscure the mechanism.
An additional scare opportunity is had by a Counselor waiting behind the corner of the bunkhouse. We'll meet him tomorrow. I assure you, it will be quite an unpleasant experience.