I like to use “Single Line Fonts”, @WillAdams will warn you that they don’t work, I disagree.
With single line fonts there is no width to the text, it’s just a single path for your bit to follow. Use a no-offset contour toolpath, and let your bit selection dictate the resulting width. I have not tried it on metal, but on wood and plastic I’ve used V bits and very shallow cut depth to get a very fine “scratch”, or small downcut bits to get a thicker line.
If I understood your question, I think this is basically what you are doing just without needing the vector editing.