Hmmm. It all depends upon the speed of the model. Several gliders I have put the pivot point at about 30%40% of mean aerodynamic chord of the horixontal surface. No particutlar problems with stability or divergent behavior of the surface.

The DynaFlite Bird of Time has the pivot at about 35% or so.

Today's servos are plenty strong. Look at the deflections on 3D-type models! Some of them have so little fixed surface that they may as well be all-flying tails, and they're hinged at about the 0%-10% point (when you consider any aerodynamic balance area).