Most formulas assume you know what CG you want, and that the problem is compensating for sweepback or taper or whatever. But those things are usually common sense and easy to deal with. The real issue is where the CG should be. To find that I've been using the following formula for about 25 years and I still surprised at how well it works on a wide range of designs:

tail area/wing area x tail arm/wing avg chord = TV (tail volume)

The 'tail arm' can be estimated as the distance from the leading edge of the wing to the leading edge of the stab, taking into account taper, sweepback, etc.

then CG = 16 + 36(TV)

That gives the CG as a percent of the chord. It's all based on "tail volume", which tells you how much power the stabilizer has to keep the center of pressure in the right place. If you think about the formula, you can see that a wide wing chord requires a more forward CG, all else equal, and a long tail arm allows a more rearward CG, for example.

The first time I used it was on a glider that seemed unstable in pitch. I stuck two quarters in the nose and it flew fine. The puzzle was that it had been balanced according to the plans. But the formula showed that the CG on the plans was wrong, and the quarters moved it to the right place by the formula -- and by how it flew. I've used it on every one of my airplanes since.

I've never found another set of plans with the CG too far rearward, but I have found that many have very conservative CGs. For example, the CG on the Balsa USA Stick 40+ was a full inch farther forward than the formula predicted was necessary. By that time I had so much confidence in the formula that I made the very first flight with the CG well aft of the position on the plans -- it flew fine that way.

Many times people complain that a certain design needs nose weight to balance, but in fact, none is necessary if you know that the CG can be farther back. You can adjust later, but it is much easier to know during the building process.

Jim