I've done what you show, but if any slight error in judgement is used for interpretting the shape, Geistware will still GIGO you an unworkable CG. The CG range of this .061 powered plane is the thickness of my pinkies.
I think my main point is that before we are allowed to use short cuts and calculators, we should learn how to "drive a stick shift" first. If a guy knows how to do it manually, then he'll have a better chance of knowing if he came away from Geistware with a workable solution.

...quite often the chalk line of the completed plane is my first draft. Similar to if you pull an ARF out of the box with no drawing or CG instructions.

...to extend key points from a model to the drawing board, block the model up squarely and use a T square or triangle to trace the outline of the object to points on the floor or table below...then connect all the dots. I like to have a datum line established first that you effectively plumb bob the plane to before you start working the outline. It really helps to weight the plane so it doesn't get nudged.