Thanks so much for all the advice & input. Great luck, our hail-mary option worked out, so the majority of our gear, including boats, will be there when we arrive. So now we are taking Tanner trail down in with day-packs and emergency gear to meet the group on the 19th (just as the high-flow event should be arriving). Very thankful as after laying all the gear out we would be taking the idea of strapping it to our backs and then hiking it down in... well seemed a bit unreasonable.
Now we are looking on how / where to keep a car for 3 weeks.
Anybody out there know of people in flagstaff who would be interested in doing a little driving very early on the morning of the 19th (drive out with us from flagstaff to GC village, and the return the car to flagstaff) in exchange for $100 and some good VT beer?