Hello Kent,
I have a tip. To solve the problem of seeing the mesh from the back side in edit mode you can add a solidify modifier to the retopo mesh. As long as the "on cage" button isn't enabled the back side of the mesh is hidden by the invisible thickness of the mesh. Now you only see the edge of the mesh from the back side. This is true if you at the same time enable hidden wire.
Best regards and thank you very much form your excellent tutorials/courses!
Staffan Wikström
