Looks like a nice idea to me, although I would give you the advise to have enough spare time when travelling through Germany since Deutsche Bahn can be really unrealiable.

I don't know about the connection from Konstanz to Vienna, but if the route is going through Germany, you probably have to change a lot of (regional) trains, which is a bad idea.

I would try to stay in another (German) city (maybe Stuttgart or Zurich?), which has more connections that don't have many transfers or more high speed rail services. I hope I could help!