Recommendation on a provider of private/small van transportation from Rothenburg to Baden Baden

Trains in Germany are comfortable, regular, reliable, and economical. Why not take the train? I would only take alternative transportation if the trains did not go where it want to go.

There are van service in a lot of places. It might help if you knew why you want van service. Do you think someone in the party is too handicapped to take the train? Most rail stations have services to help the handicapped. Steinach might not. In that situation, possibly you could have a taxi come out from Würzburg and take you to the Würzburg Hbf. From there to Baden-Baden the travel is by IC and ICE, both trains that load at platform level.

For a trip all the way from Rothenburg to Baden-Baden, any van service is probably going to be based in a larger city, and you are probably going to have to pay for the van to go round trip, so pick a major city on the way, like Karlsruhe or Stuttgart. I picked Karlsruhe and Googled "Van Service Karlsruhe" and got some hits.

Most rail stations have services to help the handicapped. Steinach might not.

The 3S people will know that and, if possible, arrange support for both
the Steinach and the Rothenburg station: 0911 2191055

As I remember, the shuttle train that runs between Rothenburg and Steinach loads at platform level and the Bahn only uses one platform in Rothenburg and it is next to the station and at ground level. The only station that should present any difficulty is Steinach where the platforms are connected by a tunnel accessed by stairs only. There are no elevators in Steinach.