The way I did my drainage, for a decked boat, is shown in the post "Graveyard Shift".
Whitewater Dory: Graveyard Shift
Brad Dimock has an updated way to do the passenger drainage which I might try next time.
For an open boat you could maybe try scuppers but there are mixed opinions on those. If you're planning on decking later I'd hold off and bring plenty of bailers, but I'm thinking you're going to be pretty busy in Pillow Rock, Iron Ring, and Sweet Falls.