Mixed Width Typeface Best Practice Ideas?

Hey. I’m working on a superfamily (weight, width, italic). Now I’d like to add styles in which different width glyphs are mixed. i.e: Extended uppercase mixed with condensed lowercase and vice versa. Currently I was thinking to have ‘.cond’ and ‘.ext’ versions of each character in the master file and allocate the correct characters for the different styles using the ‘Rename Glyphs’ custom parameter.

I was wondering if any body had a better (easier, more efficient) idea on how to tackle this