CMOS body voltage question
If by body you mean the substrate of integrated circuits then I can tell you that it's never left floating.
Substrate is always connected to something.
No one takes the risk of leaving a part of the circuit unconnected, especially in CMOS technology.

When simulating the 3D behavior of electronic semiconductor devices, simulators calculate the voltage V(x,y,z) of all the device: source area, drain area, channel area, substrate, etc.
To answer your question:
The substrate voltage V is a function of x, y, z.