Use some Lua to automagically teleport any actors over the ground to the area you defined for them to be.
I imagine it would be something like this.
Code:
for actor in MovableMan.Actors do
(tab)if (actor.Pos.X >= (right bound of your hole) or actor.Pos.X <= (left bound of your hole)) and actor.Pos.Y <= 20 then
(tab)(tab)actor.Pos.X = (left bound of your hole) + 10 + (math.random * (right bound - left bound - 10));
(tab)end
end
EDIT: You can attach this to whatever pinned MOSRot you like, just make it HitsMOs = 0 and GetsHitByMOs = 0 and place it somewhere out of the way in the scene file.