I'd just bring a flat kit and pump/CO2 and a couple of bottles. Looks like there's plenty of support:
The 100 mile route has 5 SAGs, the 55 mile route has 3 SAGs, the 25 mile route has 2 SAGs, and the 10 and 5 mile routes have 1 SAG. In addition to water and a fluid replacement drink, there will be a variety of sandwich makings, energy bars, gels, cookies, fruit, etc.