I have started a new topic "Computer Model Update". That was a mistake, I only meant it to be a new header in this thread. However, it's probably a good idea to have it as a separate thread so that the model-related discussion is in one place.
Does the model predict any rotational forces on the tower itself? It would be rather embarassing if the tower tipped with the stone into the hole! Would it be necessary to weight the rear of the tower to prevent this happening?