Hm.. nose heavy with an LA. Ok. I was going to ask you about why move the battery pack rearward, but I can understand. One solution is to move the battery pack even further back, even behind the servo tray, wrap it in foam, and tape it in place somehow. The alternate solution of course, is to add weight in the rear somewhere. You could do a combination of things.. move the engine back as far as it will go, move the battery pack rearward. then add weight in the rear.

CGr.