The 140 you have is it the DZ or the L model? I've seen both engines fly his Extra and his Edge and I have a 140DZ in my Edge and it flies it just fine, unlimted vertical, want to go vertical on takeoff?, it will do it.

Go pull-pull on the rudder and Ailerons. Put the tank on the CG and the battery right behind the firewall and you should not have to add any weight.

Hope I could help..