The 105 mile day is fairly flat riding by Ragbrai standards. Day before is short day and also very flat. Finish that day early, rest up – fuel up for an early century start as soon as sun hits the horizon. If you hit the road at 5am, you’ll have 14 hours before the 7pm target at end town (and 16+ hours of daylight if you run a bit late).
Of course, if it’s very hot (or cold), raining, or head wind, it will be challenging for many and that is where everyone should have a backup plan based on their abilities. Maybe Ragbrai should designate an additional “meeting town” on century day to allow teams to plan a safe pickup point later in the day.
If weather is mild, maybe even a little tailwind, I think most riders will be pleasantly surprised to find that it wasn’t as hard as they expected…