A Pound of lead!!
#33
Good plan to move the servos and use carbon rods. Might not quite get you there; if not, you can make a battery box in front of the firewall with a hole for the connector to the rx. Then if you still need just a little more, hopefully a heavy hub will get you there. I hate adding much weight too. The design has a short tail and a small stab, so the CG probably doesn't have much leeway.
Jim
Jim