I have used a coupler from Jamara before that works pretty good. It has spaces in it for three 4-40 rods to slide into and lock in with a set screw. The two outer holes connect to the rods for the elevator halves, the center hole goes to the servo. That way, you can adjust and fine tune each pushrod to get to neutral. There is also a precision bell-crank available, I think I got one through Central Hobbies. Anyway, it mounts in the tail of the plane and basically mounts two "servo" arms onm the outside of the fuselage on either side, with a control arm concealed inside the aircraft. The device is lighter than two servos would be back there, uses ball bearings so there is no slop, and allows for short, firm linkages to the control surface.

I've been through a variety of methods because I never can get a conventional y-rod to work out correctly, and I always like to try and tech my way out of a problem.