The best way to mark the CG on a HotSpot is the way Bob Wilcox does it. Put a piece of masking tape on the leading edge of the wing about 6 inches out from the vertical fin. Using a ruler held along the leading edge and butted against the vertical fin, make marks on the tape at 7 and 7 1/2 inches. I fly my HotSpot with the CG just ahead of the 7 inch mark and it flies beautifully.