Thank you. That is very helpful. The idea of riding solo is appealing. I guess there are a lot of riders along the way to keep company with.
I have done some of the MT portion of the TransAm three times in the last few years, including back in June of this year. Met lots of other people along the way. Thus June I met two guys who were travelling together who had hooked up informally with a solo rider. A few days later I spent two nights at the Bike Camp in Twin bridges. Two solo riders and a group of three stayed there. All were heading east. In 2014 I camped in Jackson with more than a half dozen other riders doing the TransAm.
I also agree that riding alone or with maybe one or two other people tends to lead to more "intimate" interaction with locals. My first tour was ACA's group Northern Tier tour with a total of 13 people. The neatest interactions with locals happened when group members were on their own or with one or two others. For example, me and one other guy had taken a side trip in Indiana to visit a bike shop. While we were on our way to meet up with the rest of the group, we stopped at a café for breakfast. We ended up talking to a farmer who was the town's former mayor. After he left for work, we asked for out check. The waitress told us the farmer had paid for our breakfasts. Doubt any of that would have happened if there had been a half dozen or more of us.
After that trip ended, I rode home down the east coast alone and was the recipient of far more offers of kindness that I did when I was with the entire group.