I've always had a problem understanding this "pendulum" effect, or even finding it in text books.
(I just checked "Aerodynamics for Naval Aviators".)
A low CG can increase the leverage of a high vertical tail, (and I suppose the leverage of the fuselage in the float plane case), but for anything to do with lift differences between wings, (eg classic dihedral), the forces act out along the wing-span, so the vertical CG position is second order.
High wing aircraft get their extra lateral stability because the fuselage forces the sideslip to move around it: the into-wind wing sees a higher AoA, the out-of-wind wing sees a lower AoA. This can easily be equivalent to 3 degrees of true dihedral.
For low-wing aircraft the effect is reversed, and designers tend to give them more real dihedral to compensate.
I am assuming a rigid aircraft. For hang-gliders I imagine the pendulum effect is very real!