Hi, I used C4D for a long time, but now it is so expensive that I had to change my SW. But I have collection of C4D models and I had solve how to export some models to SU. I found one solution:
Basically I use demo version of C4D and Riptide plugin for Cinema. Demo version of Cinema opens C4D and is capable running plugins all the time. Riptide plugin is capable of importing / exporting OBJ very well.
I don't know if it works with very last Cinema demo-version, I use older demo version and Riptide.