When I haven't a clue as to where the CG is on my unorthodox scratch builds I use this technique. I get a large cylindrical pencil and put it under the plane and roll it back and forth until the front and the back do not touch the table. This is the "balance point" on the plane. Then I measure approximately 1.0 inches forward of this balance point and I mark it as my CG (approx). I put my battery in and move it to and fro to get the plane to be level when the pencil is under the "CG" mark. This mark is an approx CG point but it is a good starting point. I find that on my jets I still need to move the CG slightly more forward but not much. chas
But all you are doing is finding the center balance of your plane which has nothing to do with your wing design. Sorry I don't know all the right terminology . The cg is based off of the wing area, design and size front to rear and all that other stuff to come up with a balance point on the design of the wing, not the weight of it. You are just balancing the weight. If I add 4 servos to the rear of your plane and you do your method the cg will be even farther back .