There are lots of towns and villages on the route which make a great effort to support and enjoy the event. If you're not after a quick time, then it's worth taking a few minutes out now and again to celebrate with the locals...they will love you for it.
The control at Loudeac (445kms) is a riot. Easy to waste time but a shame not to soak up the atmosphere.
Similarly, there will be a 3 day party at the village of St. Martin des Pres approximately 480/730kms into the ride....great place to grab some frites if you bounce the food at Loudeac.
Sizun at about 575 and 655 kms has a chilled festive feel to it after descending or before climbing Roc Trevezel. Mamers at 1080 kms is another great pit stop during daylight (ish) hours.
Finally, if you finish between midnight and 6 a.m in the morning, there won't be too many people around to cheer you home....but after 10 a.m, well, it's an emotional experience.
On the 90 hour start, the more you can stick to a 'normal' sleep routine...albeit truncated, the better you'll feel in the latter stages.