I've been thinking about what Joe wrote about Coils. I had originally not given the dragon drives because it represents an enlightened being, devoid of drives. Thinking it over now, I realize the dragon isn't enlightened, but a bodhisattva. A bodhisattva is someone who has held back just short of achieving enlightenment in order to help others reach that level.
Thinking of it that way, it would have made sense to give the dragon one pseudo-drive for each character on the trip. These drives would be used to create minor manifestations of the dragon, rocks that close like a hand of claws, currents that drive boats towards danger, and the like. As each character gives up his wish drive, one of the dragon's drives would be lost as well. Unlike drives, the dragon doesn't gain Flow for each drive lost, because the character's Flow is partially them working with the dragon anyways.
How does this sound? Any other suggestions?
I'd also rework the pebbles and day-tracking into a board (in the shape of the river) with a pawn moving along the 45 spaces (or 114 for the amazon). If you accumulate 3 (instead of 2 in the original game) delay pebbles, they're discarded and the pawn moves back by 1 space. If you accumulate 3 rush pebbles, they're discarded and the pawn moves forwards 1 space.