As far as 2 up riding, I don't think my wife would ride really all that far anyway. We are both 5'9, I weigh about 200 and she weighs about 140. She probably would not ride more than 100 miles each way on the bike. I would get the America two person seat and a backrest for her, anyway. Does that sound reasonable for the comfort on the SM or BA?
By the way, for those that have changed to a 19 tooth front sprocket, what is your RPM at 60 MPH?