Terry, the flyable CG is relative to the wings' chord. You have a constant chord wing, so just simply go 25% back from the leading edge and that is a good starting point. For example, if the wings' chord [ailerons included] is 10 inches, then the CG should be 2.5 inches from the L.E..

I have noticed before in another thread that you wonder if this plane came out too heavy? If so, the CG will become very critical...

The airspeed will have to increase to provide enough lift for stability. This is usually the point where some models aren't too much fun to fly, they are just more of a challenge to keep in the air.

You should be able to build a 4 channel 1/2A plane that is light enough to fly very slowly with a fully symetric airfoil. Years ago I built a Airtronics QT kit that ended up not just too heavy but tail heavy, also.