score:3
At the moment, there is no such a book. In amazon.de and rhinecycleroute.eu there some books about this cycle route. I think the best choice are the 3 books Bikeline Radtourenbuch, Rhein-Radweg. Each book costs about 13 EUR, the size is about 22,8 x 12,1 x 1,5 cm, and the weight about 350g.
As I already said, it's not what you want but there is nothing better.
Upvote:4
On Everytrail there is one person who set out a route. (like @Dirty-flow) He mentions Rhein-Radweg 1, Rhein-Radweg 2 and Rhein-Radwg 3.
If you are in to apps, I would recommend the Everytrail app, as an alternative to a set of books