I always use a formula to get a starting CG with any plane, even if the kit or plans specifies one. I assume the CG calculator, above, works from the same formula, and I would advise you to use it. Rules of thumb, like 1/3, work well enough for many planes, but not for all planes. If the stab is curvy, get the area by cutting from a rectangular piece of cardboard and use a balance to calculate area.

Once I have the CG figure I want to balance to, I cut two thin pieces of masking tape, measure, and stick to the wings spanwise, and then put my fingers on them. It's too hard to tell where your fingers were otherwise, but you don't need balancing machines. With this method I can tell right away if it is tail heavy or nose heavy.

Jim