While I was in Hong Kong last week, I found some cheap digital scales (A$12 each).

I decided to try the method used in light aircraft to find the Centre of Gravity.

I put the model on the scales as shown and measured the distance between the main and nose wheels. A simple Excel spreadsheet gives the CG as a distance from the Main wheels or any other point such as the leading edge. Works for a taildragger but the model needs to be level.
It is a simple matter to add or subtract weight from the nose to get the correct cg.

Ok I know it is a bit of overkill, but I found it interesting.

These scales have a max of 5 Kg, so the model weight would be limited to just over 10Kg. Big enought for all my stuff.

Regards