I wouldn't cut the plane open to move the battery pack. If you can install some eye hooks and strap it to a former or something, that will work fine. I just had a buddy's Avistar for a few days, with my 46AX, and the plane flew great. We mounted the battery as far back as possible. There might have been some lead weights already installed under the stab on that plane, though. Also where did you find the CG location? Are you sure it's right? Should be 3.25in back from the leading edge of the wing. Also your fuel tank should be empty when you balance it.