Your measurements of overhang being 3', 4' or 5'.... are those measured when the hoop is at 10' elevation? And if so, do those measurements increase when you decrease the elevation, say to 8'?

Yes, overhang is defined as the distance from the post to the backboard when the rim is at a regulation 10' height. The overhang does change as the rim height changes. There is a table in the instruction manual that shows overhang at different rim heights. It's out the furthest when the rim is at 7'