Thor normally sells parts through a dealer.. Thor customer service may help with part numbers and some idea if the separate doors can be installed on your model.
The doors, shipping, and install may be expensive...
My 24ST has a pleated folding door across the opening at the bedroom. It is seldom used because the rear bathroom door serves the same purpose when open.
The pleated door is Thor original- but is made by ASCOT. it hangs on a track and may be a better option for privacy across the bathroom.