Sounds like fun. It is fully supported. As a ride leader, she will be driving the van sometimes. This is from the wiki:

Most days during the 8–9 weeks of each trip are spent riding. Participants ride an average of about 70 miles per day. Overnight stays are arranged in advance of the trip, and are usually at churches or other community centers. Occasionally, the overnight stay will be outdoors. After breakfast and packing up, riders perform a quick cleanup of the overnight location before heading out. Each ride has a van and trailer to carry the riders' gear. Once the trailer has been loaded with everybody's gear, one of the trip coordinators (the duty of driving the van is rotated between the four coordinators) drives it out and sets up a rest stop on the route where riders break for lunch. After all the riders have eaten lunch, the van and trailer continue on to the destination for the day, or to set up a second lunch stop, on longer days.
I think she'll be fine. Wish I was 18-24! I'd try it.

Karen