@alex, thanks for stopping by. I'll do my best to explain. The image below is basically what I'm thinking. Apologies for my hand writing.
There are two things I've left out. One is that this spine modifier idea doesn't have to be a mass, or even start with a sphere. It could be a single point in space, or even 2d, only a gestural idea (bottom left ref, went with a 2d gestural idea). But I'm usually imagining 3d spheres, the lines wrapping and touching points along those spheres, and chopping off parts and carving them up.
It may not be clear what problem I'm trying to solve. My figures would often have this disjointed look, like torsos and pelvises just happen to be wrapped in skin without a feeling of attachment. That feeling of attachment comes from the natural motion of the body. If you lean your hips forward, your torso tilts back. If you lean your hips back, your torso comes forward. The same goes for side to side, etc. To a lesser extent this happens with other body parts, but it's very noticeable in torso and hips. That's the thing I've been lacking, and this is how I make sure to think more about it.