I've thought of fitting an AC unit, however, as yet I have not located one that does not require me to do a major refit. Other options take up too much space on the decks with their generators. So I'm planning to use the fans.
As the refit of the cabins go underway, I'll fix these in more ideal positions. It's cost effective, however, I'm unsure if it will bring as high a level of comfort as AC. It's satisfactory at least.