The best way to check and see if your CG is where you want it for this type of plane is to roll inverted. You shouldn't need more than a very slight touch of down to keep the nose level. Many 3D ships are set up to fly hands off inverted, or even climb. I prefer to have mine set up needing a touch of down. A tail heavy set up is not needed for good 3D. So its open to interpretation and preference, but if you need more than a touch of down move the CG back. I had that plane for a long time. It will tolorate a very wide range of CG placement with no ill effects. You wil find, however, as you move the CG back coupling wil change and pitch will become more sensitive.