I just got done building my Avistar but it is very nose heavy. I moved the battery and receiver back to just in front of the servo tray but it's still nose heavy. I added about 6 oz. of lead weight right behind the servo tray but it still needs more. This is with an empty fuel tank. Is there any way to add weight further back in the tail or should I continue to add weight behind the servo tray until it balances? The plane weighs about 5 lbs. and is powered by a TT .46 engine. Thanks.