Joking aside, you might want to do some web searching on field testing of climbing anchors. Folks who do that sort of thing seem to use some combination of hydraulic device for an steady, even, slowly incrementing pull. For the actual measurement they use a various devices called a "load cell" or "pull gauge". Might cost a couple of $K to buy it all, but maybe you can rent or borrow? You also might try to find a college engineering department who will let you do it in a lab as a project by your boy scouts?

Good luck. We are all pulling for you!