Thanks duststorm for the pointers. Let's start over.
The goal is to create a clothing template (a body stocking) that would flow over the standard Makehuman mesh, without the need to hide the body underneath.
I have decided to use the Alpha 5.1 mesh as my underlying model, because of the constant demand for the T-Pose, and because the deformations in the T-pose are more severe than with the A-frame.
This requires the integration of several Blender techniques: (1) the new retopology tool--the magnet icon; (2) the mirror modifier; (3) adding new primitives in Edit mode, and joining them to a center polygon.
Here are two images, showing all three techniques in action: