Captain, I wasn't arguing about what would happen with those experiments. I just couldn't figure out what the phenomenon was that you were describing. Now that you've told me what happens, I can benefit from your experience. I wish what people were telling me had sunk in when I had my hexagon airplane. It's flaps were too big and too stiff for the tail, with the result you describe above. I had to operate it with a way-back CG.
I think you mean by "excess lift" that a given airplane has either too much hinge moment to rotate the airplane adequately or too little net pitching moment to rotate the airplane adequately, or some combination of those. In the case of the Impact, it was probably too little net pitching moment. Both too much hinge moment and too little net pitching moment can come from flaps that are too big or, especially, have too much chord for a given airplane configuration. Flaps do help with lift, but it's the flaps' other, nasty effects that too much flap gives too much of.
There is another phenomenon that I thought you might have been describing: where at high lift coefficient, the restoring pitching moment peters out, making it hard to hold the target loop radius, hence my question about the propensity for the turn to tighten up. Igor discussed this, I think, in his Stunt News article. Looks like that's not what you mean.
Assuming no side force component, lift is just the component of the aerodynamic force on the airplane in the direction perpendicular to the direction the airplane is going; drag is the component opposite to the direction the airplane is going. I think one should use technical terms as they are defined, rather than to mean something else.