RE: East coast Bowfishing (nj)
I would look for shallow, weedy and/or muddy areas. Carp are generally lazy and will sit more in slack water, or water with very little current-movement. Look for 'puffs' of silt in shallow water. That is almost a sure-sign of carp feeding. But be sure it's a carp before you shoot. I've drawn on many soft-shelled turtles and snappers.
If you're using a canoe (I assume so since you said Gumman), look as far ahead of you as you can see in the water. Carp have good eye-sight, and if you can see them, they can see you. And they don't usually hang around long once they see you. Move slowly, and try to keep your bow up as close to your drawing position as you can to keep movement to a minimum once you see the fish. Movement sends them off pretty quick. That's when you'll get your 'running-rabbit' shots.
Remember that water refracts light, like how your fishing-rod looks like it's bent when you stick the end in the water. You'll have to aim lower that you'll want to, or else you'll shoot over them. Nothing can help you with this other than practice.
Hope this helps. Good luck, and post some pics if and when you shoot some.