Late August will be tough. I'm sure you could do it in a canoe, kayak or maybe even a small cat (you know "personal pontoon", kick boat or what ever you want to call them) or possibly a very small raft (mini me esq). I'd wonder if a lightly loaded mini me wouldn't float higher than a canoe? but the other problem would be width - harder to find slots to fit it in...
I've done 2 sub 100 cfs floats in fully loaded rafts - 13'ers. Both earlier in the year (i.e. we got some help from side streams that pumped up a bit on the trip). I would not plan a late august trip my self. There is essentially no chance of flows capable of moving normally loaded rafts and that's what I like to do. The only prayer you'd have to get bigger boats on would be a perfectly timed series of T-storms. Dory, in late august? Not a chance - you'd be walking it and replacing the bottom before your next trip.
I do know folks that do it regularly in the late summer early fall in canoes and they have nothing but good things to say; but it's always work making miles. It's an awesome trip and if that's your only option then do it. Just don't expect it to be a walk in the park.
MFWP's suggestions are typically conservatively high as has been noted above. In actuality what you can get by with depends on you. For some folks the suggested flows are right on, they don't know how to read water and don't want to learn and they certainly don't want to drag, for others you can get by with a lot less depending on experience and expectations. I say this because you'll hear a lot of varying opinions on minimum flows per type of craft. For me it's roughly 200 for normal raft trips, 150 if everyone is ok with some extra work. 100 maybe, if we're super light, one person per boat and everyone sticks together to help out when needed.
Yesterday's gone on down the river and you can't get it back. - Agustus McCrae