My boat is the "Blue Heron". The fist was the "Kayenta Queen" and the person I sold it called it the KQ II. I haven't painter them either but remember hearing about a guy using latex caulk. Not sure what he used for coloring.
If you're in the Denver area, check out whitewater inflatable technologies! Zach and his shop do lots of logos for big companies and he couldn't be a better guy to work with.
Ours was the Red Hot Chile Pepper and we're still working on a name for our new orange boat!