I am far from the expert on this, but I will throw out three things to think about that have bugged me enough that I have taken steps on my end to address them:
1. The seat / my backside in hot weather. In sub-75/80 degree days I can ride forever, but I had two rides in hot, humid weather that were torturous.
Maybe the weather will be cool, maybe you skin is tougher than mine, but if you think it might be an issue you might want to plan for that. Sheepskin, various powder (e.g., Monkey Butt) and triathlon shorts (or similar, wicking, cycle shorts) may be the solution once you decide whether or not that might be an issue. I have a Corbin seat, but I can't blame the seat as it is fine for me in cooler weather.
2. Wind noise. I added a wind screen, a collection of earplugs and a new helmet after my first long highway ride on the T120. What is tolerable for an hour gets old after after awhile, but this, at least, I have managed.
3. Light. Might not be an issue in a group ride, but headlights / aux lights you are comfortable with for whatever roads / speeds you will be riding in the dark will help make it an easier trip.
Good luck, sounds like fun.