If it helps i was never able to make WP-touch (free) and wp super cache (also free) work together.
The cache was either all mobile or all desktop for everyone.
I solved this using "W3 Total Cache" instead of super cache. Once you get used to the interface they both do the same thing (store a plain html files of all your pages), only difference was that "W3 Total Cache" actually works as intended with wp-touch.