My wife and I ride a 2005 Cannondale RT. My fit looks and feels exactly like my road bike, but my wife decided that she wants to ride upright. She had me rotate the cow horn bars back 180 degress so probably 75% of her weight is on her butt. I want a happy stoker but inevitably she developes serious sit bone pain at 30 miles, and I think she is getting less enthusiastic about long rides.
I tried to talk her into putting more weight on her arms and feet but she really hates that aero position. My challenge is to allow her to ride in her regal postion in comfort. I like the idea of regular stand ups every 15 minutes and we'll try that. Maybe in this unusual situation a fat seat or gel cover? Some thing tells me that there others in my demographic (the empy nest one) who are dealing with the same issue.