Thanks for all of the replies. I have put the battery pack under the fuel tank. CG is measured from the leading edge on the TOP wing at the ribs where the wing pylons go (2.75" in from the LE). This puts the CG straight vertically above the bulkhead that is the BOTTOM wing leading edge.

Unfortunately I did check out all of the threads on lighting the fus., but after construction (doh). Have built many planes but could still be screwing up somewhere CG wise.

I thought about removing the covering and adding lighting holes but did a killer job on covering so would hate to do this.