Here's a picture of the plane I'm basing my judgments on: It's a Stinger with enlarged tail surfaces. If you look at the horizontal and vertical, the lime grees parts are 4" wide extensions that I added to the rudder and the elevator. That is, the tail per-plans is the blue and white part, and the green is area I added on myself. 2x elevator extensions means I increased elevator span by 8" - which gave me a stab span at least 1/3 of the wing span.


This plane balaced neutral right around 40% chord. That is, I could flip it inverted and level, and it would stay level. A little more tail heavy, and I'd flip it inverted and it would push toward vertical. However, it was completely stable and well mannered otherwise.
In fact, I once had 4 oz nose weight (on a 20 lb plane) break lose and slide all the way to the tail cone. Then it got a little divergent, but not real squirrely - that's what a big tail does for you.

With the length of the tail boom on this plane, it seemed to have a good balance between tracking and tumbling maneuvers.