I have not used the sleeve, nor I have seen one, but the idea makes allot of sense.
I would take it to a local loft and see if they think adding the UV is worth it or not. Or try Sail Care out of Ford City, PA. I have had great experiences with them and highly recommend them. They would tell you straight up if it was worth it or not. They also have their annual cleaning discount going on right now so it may be worth the call. (their cleaning process is a bit more involved than just "cleaning"