My CG was originaly 1cm behind the wing tube, but the model tended to lift the nose on loop exits, so I moved the battery fwd of the fuel tank, I don't know your set up, but if you have one elevator servo under the rudder servo, tank on the CG, then put the battery just fwd of the tank, if you are using elevator servos in the stabs, then put the battery agains the firewall.

My plane balanced very well, just moving the battery, the CG should be at the wing tube or 1cm aft, depending on your flying stile, but it flies better for me on the wing tube.

Regards