This is a great write up!
One suggestion to maybe make things a little easier – while using the surface checkbox, use the “embedded depth” to set how “deep” the text is on the surface.
In this case, the thickness doesn’t matter.
When you then change the type to negative part, the embedded depth will be taken into account to cut into the surface. This way you can position the text on the surface, but then not bother “moving it” into the surface, but relying on the embedded depth instead.