BTW, if you were to use the aft CF tube in Tall Paul's righthand plan as the pivot for the stabs, you would simplify the work needed for your redesign. Since you're working at the rear of the airplane, you'd benefit from a very slightly lighter structure. And the hingeline of the stabs would be reasonably close to the .25C of the MAC. Since you're not bound by anything at all, simply place it slightly farther forward than in that picture or not.