Instead of just a spherically blunted cone, the cone is two spheres connected by a conical section that is tangent to both spheres. The larger sphere is the diameter of the base of the cone where it meets the airframe. The smaller sphere can be defined however one wants, but a logical parametric model would make it a percentage of the larger sphere's diameter. The other parameter needed would be either the distance between the sphere centers, which would additionally define an overall fineness ratio, or the overall fineness ratio of the cone, which would then define the distance between the two spheres. The cross section is simply two circles with two tangent lines connecting them. Rotate that about the line connecting the centers of the circles to define the nose cone.

This seems like such an obvious way of giving the simple blunted cone shape a tangent union with the airframe, it blows me away that I haven't seen it in any literature or represented in any nose cone design. Is there something I don't know about aerodynamics that would make it a bad idea? I can't see how it would be worse than the simpler blunted conical shape that is widespread, and I don't know that it would be a lot worse than something like a blunted ogive.