I'm trying to map out the middle leg of a three region trip, and wanted some feedback. We'll be coming from London by plane and the plan is to leave the area for Paris by train. London-Munich seems to give me more flight options than London-Salzburg would, so call it a start point. Perfesser Mouse wants to drive the autobahn, so pick up a car at either Munich airport or Munich train station downtown.

From there, I'm thinking the Garmish-Partenkitchen/Innsbruck area (castles, Zugspitze) followed by Berchtesgaden Nartional Park near Salzburg. Is it generally okay over there to do a one way rental and drop a car off in another county? Dropping the car off at Salzburg airport and a nice regular 10 minute bus ride to train station at that point seems less of a hassle than looping back to Munich and dropping the car off there, even if we end up having to add a train connection in Munich or Stuttgart in the process.

Provided it's doable like the rental car companies seem to say it is, which is my question.