I know Royal Caribbean doesn't offer anything "less" on any of their ships.
HOWEVER, if you are looking for a cruise line that does full nudity, there are small ships that offer this.
Look in the very back of any Travel magazine in the advertisement sections. There are a few companies that do nudity cruises (or some sort). I've seen it I think it was in Travel & Leisure magazine? You can get any of these magazines at your favorite bookstore or anyplace else that sells magazines. Just flip to the very back & check out the advertisements.