The one I built also had Cheetahs, but all 4 batteries are near the forward edge of the cockpit. Granted this is the Su-27 model so perhaps the canards add a bit of weight. But then, you have thrust vectoring which we did not. I think we balanced just on the front edge of the main spar. Seems crazy to have to put the batteries basically in the tail and still be that nose heavy. We also did not have a cockpit or pilots in it at the time, is your cockpit that heavy?

Are you using electronic scales or supporting the plane at the balance point?