I am about to look into the Chandrasekhar limit. This as I understand it uses 4 values. The mass of a proton, the gravitational constant, Planck's constant and the speed of light. This may turn out to be a way to find my lower density limit with rs, the Schwarzschild radius, being an upper density limit. As I see it no matter the size of the mass involved g must go infinite at this radius along with time dilation and length contraction, except that that would be counter-intuitive. Sounds like a quantum state to me.
As for uncertainty and the Planck mass I would think that density may reduce uncertainty as at infinity there is no time or motion. the particle is effectively at every point in the wave function.
As a correction to that last sentence, the wave function may well cancel out completely and flat line. This in my opinion should be equivalent to an absolute zero state and being an absolute would mean the Schwarzschild radius is also an unattainable absolute. The big problem I am having is finding a function to relate density to field strength without loss of mass through a brane. This I really don't like as it starts running into complexity, which is what I am trying to avoid.