Aah... Now you're learning the value of an isostatic mount
most of the time my scopes are un-clamped, just the bearing friction is enough to keep them in place ...
If the plank was a bit longer you could have another scope on the other side to balance it ... Great for outreach nights as one can have the eyepiece low down for the littlies, the other scope with its eyepiece higher for yourself and the taller kids.