I saw on the Travel & Leisure website that there's a new hotel opening in Kruger Nat'l Park. Called "The Train on the Bridge", it's literally that. I can't see Tauck using it, but you never know. You can see it here:
https://travelandleisure.com/hotels-resorts/kruger-shalati-kruger-national-park-train-on-the-bridge-hotel