You'll always meet others wanting to go your pace. I've done STP 1-days solo, without paceline help. Just don't sleep in, plan on starting by 5:00. You'll probably be pleasantly surprised and although you'll be worn out at the end, wonder why you worried so much. Again, this applies only if you are well prepared.

P.S. I'm assuming you're doing 1-day. 16 mph is at the low end of the road bike food chain, I did that on a MTB, but you'll still find others in the same boat. The biggest thing to worry about is forgetting to enjoy the ride, spending too much time on mental time/distance calculations.