Well, firstly, where do you have your tailfeather servos mounted? You should mount them so that you do not need any extensions to plug the servos in (unless the plugs are very short).

I mount my equipment based on where I mount my receiver, which is usually about an inch back from the TE of the wing. My servo leads are about 12", so I mount them about 11.5" back from the TE of the wing, then use long control rods to connect the tailfeathers. Usually, I mount my batteries about 1" or so in front of the wingspar, and there is plenty of room to adjust CG.