This is only 100 miles. Just plan ahead and carry what you need. Make sure everyone in the group tunes up the bike before the trip, and is "ready".
If you have 3 or 4 people, you may be able to pool supplies somewhat. For example, if 1 spare tire would work for the group, then carry 1 spare for the group. A few tubes. Patch kit. Etc. Fiber Fix? Tools? Boots? LIGHTS. Emergency overnight supplies, matches, water filtration, etc.
I personally wouldn't use a "SAG", but it never hurts to have a couple of check-in points, and a preplanned route left with someone that will come looking if you don't show up. There are very few places that you couldn't overnight for a single night, but someone should come looking if you don't show up by noon the following day.
Don't take excessive risks that might send you and your group flying off a cliff face.
Pack-it-in, Pack-it-out. Don't be exceptionally rude on the road, and hopefully if you have a true emergency, the locals will be willing to lend a hand.