Camo finishes are nice for outdoor gear because if you get a scratch you can cover it immediately with no problem. I assume your boat is fiberglass and I would think good oil based paint would stay on good, I wouldn't use latex. It's a little hard to find dull oil paint I suppose waterfowler suppliers have it but it's probably expensive. Keep you eye open at the hardware store and over time you'll probably find what you need. Could be some old greybearded hardware man can mix something to give a flat finish.
Remember if having a camo boat makes you want to go duck hunting, you'll need to do the inside too.