Check out this page. Lots of good info here along with the formula for the Horizontal Tail Volume Coefficient and how to relate it to the CG. The higher the TVC the more damping the model will have. Also a higher TVC puts the neutral point further back so your CG should follow.

It's all down near the bottom of the page but the first part explains where it's all going so be sure to read it from the top.

http://www.bumpygreen.co.uk/Articles/cofg.php