Well, if you can manage to get the controls in there, the 1/4 MAC is what I am talking about.

What about area proportions? Like 33% or 10% of area in front of pivot?

Your mistaking this for a traditional elevator. wsmalley is asking about an all-moving stab... big difference.

I recommend the 1/4 MAC, but your going to need a pretty stiff area to put the pivot at (read THICK). By making it an all-moving surface your tail loads are going to go up quite a bit.