We bailed on the night laps - it was the one thing I wanted to do, but it didn't work out. We ended Saturday after the 7:30 lap. A hot shower and a chicken fajita later, it was bedtime. We entertained the idea of getting up at 4:00 and rolling out at 5:00. By the time we hit the tents, we decided sleep was a better idea.
The solo group was huge at the start. My mistake was intentionally starting at the back.
Assuming you're not competing seriously (as in the guy who did 17 laps - wtf?) and you can do more than a lap or 2, solo is unquestionably - for me - the more enjoyable way to do it. This becomes moreso if you have a friend to ride with. Obvious downside is if you don't have remotely similar goals or abilities. But the guy I rode with had a SS. Even with that disparity we generally kept the same pace with no problems.