"They both seem unstable and prone to stalling and poor penetration. "
Pitch instability is the main indicator of the cg being too far aft. Add enough nose weight to get the plane pitch stable and then see how you like it. The correct cg is the position where the plane is pitch stable enough for the way you like to fly. I have not run across a plane that could not be made pitch stable by moving the cg fwd.
Did you try a dive test?