good luck on flows, the upper box should be dried up by then, looks like it's below 400 and dropping. It's not really worth it below 300. If you do go paddle a creek boat. As far as the upper box, the shuttle is a breeze, the road parrallels the canyon rim. It's the hike back up to your car at the takeout that is a bitch... Turn off the main highway at the big brown Rio Grande Wild and Scenic River sign north of Questa, and drive about 6 or 7 miles to get to the putin(Chiflo Trail), then another 6 or 7 miles to the takeout(Little Arsenic Trail, this is where you want to camp).