In my years as a prof. aero. eng. we had the opportunity to try a lot of things. In the 100 years since the Wright brothers a lot of things have been thought of and tried. Honestly there is not all that much that is new. Most modern aero work is just refining designs as different structural materials, such as those that allow things like the extreme aspect ratios of the gliders, become available.

I have heard it said that aero types working on transports (targets) would sell their moms for a one drag count reduction. Aero types working on aerobatic airplanes (fighters) would do the same to get a few degrees of angle of attack before buffet onset occurrs. There have been a lot of man hours of work to try to get any edge in airplane design.

Saying all that I have to believe that the configurations that we see presently in use are in all honestly pretty well optimized. What you don't see in a flying design are the hundreds of pertubations that were tried in the wind tunnels. For instance your horizontals. If someone had even a hint of performance (drag or maneuvering) benefit it would have been bolted on during the wind tunnel testing.

This is not to say that there is not anything new left to be discovered but it is almost the case. We prof. aero. eng. types like to think that we are free enough thinkers to have worked out optimum configurations for most stuff.