My husband and I did the tour in September and I had to think back to remember if we had any solos in our group. We did - he was a gentleman in his late 20s, early 30s. For lunch he was seated with another couple and the guide. I think it would have been great to have some one on one conversation with her about her experiences.
So much of the time you wear a headset so you can hear the guide so I'd think it would take away self-consciousness of being there by yourself.
I traveled for years on my own ( Disney, Vegas, Cruises ) before meeting my husband so I know your concern, but I think the way its set up you'll be fine.