How should I handle alternate forms with a cycling font?

I’m finishing a font that uses CALT to cycle through variations of the same glyph following the tutorial. So I have Eng, Eng.ss01, Eng.ss02. But I have both versions of Eng (uppercase style and lowercase style.). I’m not sure what the best way to make this work is. Ideally I would put them in a stylistic set but obviously that doesn’t work here. Has anyone else done this and if so how did you handle it?

Use a different suffix for your alternates, like “.alt01…”. then add “Eng.ss03.alt01…”

Personally I like to use .cvXX instead of .ssXX