RE: installing top hinge
I wouldn't mind hearing about top hinge methods.
I used Robarts on my last kit with beveled ailerons/elevators/rudder. I then covered them with a single piece of Ultracoat. The stab sheet went from leading edge to trailing edge of the elevator, and the same for the other control surfaces. There is no bump under the covering from extra strips underneath. I don't see any way a control surface could become separated.