I too use the 3/8 or sometimes I make up a servo tray. One thing I do on all my planes, well, the ones that come out without a CG problem, is to assemble the plane as complete as I can then set it on the CG machine and set the servos and gear on the plane with some tape. I try to get the CG close before I hard mount anything. I do this with the plane in the bones. Then I take it apart and cover it. When it's finished the CG is easy to set. Just a little something I do and a trick I haven't mentioned in a while.