Several airlines have a stigma about taking kayaks as luggage, mainly because they still think kayaks are 12 ft long and made of glass. One of the airlines, Delta I think, had a big fiasco during one of the last two olympics where they broke a bunch of the US team's slalom boats, and have therefore adopted a strict no kayak policy. A few other airlines have followed suit.
Fear not, however. I've flown with a kayak to Alaska, Mexico, and Ecuador, and a couple of those were on airlines that had a no-kayak policy. All of those trips were post 9/11 as well. Here's my strategy:
1. Call the airline and ask about their kayak policy. If they say no kayaks, say thanks, hang up, and call again to get a new person.
2. Ask about their surfboard policy. Most airlines charge $40-$75 for a surfboard.
3. Tell them OK, well, I have a surfboard-kayak. It's the same size as a normal surfboard, and made of plastic, but you sit in it instead.
4. a. Most agents will say ok, if it's the same size as a surfboard, no problem. When they do, say thanks, ask for their name, and ask them to put a note in your file saying that you discussed this and that you're planning on bringing it.
4. b. If the agent says no, say thanks, hang up, call again and repeat.
5. When you go to travel, wrap the boat up in a tarp or something. Doing what you can to shape it like a surfboard doesn't hurt. Label it clearly with "Surfboard Kayak" in as many places as possible. Maybe pad the bow/stern a little bit as well, to avoid damage. The people checking you in will most likely have no idea what a surfboard, kayak, or surfboard kayak look like in the first place, and quite frankly won't care anyway, so they shouldn't hassle you too much. If they do, that's what the note in your file is for.
I've only travelled with a playboat, but modern creekboats are still smaller than the longboard configurations people travel with, so it should still work, I'd imagine.
Hope this helps. Sorry it's so darn long. Have fun down there.