hi noahj;
some questions about this part of your post:
trying to achieve this myself by changing WP_CONTENT_DIR. to something like UPLOADS. obviously doesn't work totally :) - I get the caching files in the right place but I'm doing something wrong because the stylesheet is not applied.
1. "changing WP_CONTENT_DIR. to something like UPLOADS" did you also change WP_CONTENT_URL (you should)?
2. "I get the caching files in the right place" means the URL's pointing to CSS/ JS in your HTML are correct?
3. "the stylesheet is not applied" means JS is working? or is that broken as well?
4. "the stylesheet is not applied" when you look at the contents of the aggregated CSS files, is there anything in there, or are they empty or do you get a 404 (page not found)?
kind regards,
frank