Take a canoe
That's slow flat water, especially when it's low, best done in a canoe. If/when there's an upcanyon wind, you'll be hating that raft. I led a couple of elderhostel canoe trips down there way back when. If they can do it, you sure can.
Nice canyons. Great camps on the big sandbars. Bring some shade (umbrella, river wing, etc). have a great trip.