Here is the Rod holder I use on my Cobra Expedition:
This rod holder has worked great as a deck stepped mast mount and also as a fishing rod holder. The Base of the unit accepts 1/2 pvc pipe that you can use to make a camera mono pod. Also Scotty sells lots of accessories that plug into the base. Fishing rods are subject to great strain and I've tested this holder for winds up to 20 miles per hour with a one meter sail. I suspect I'll want the sail down before it ever breaks.
Naturally you'll need to strengthen the deck of most kayaks that are not made for mounting a rod holder. Even when you have a fishing kayak, they are usually not set up for anything stronger than freshwater bass. I usually use a block of 1/2 inch to one inch thick piece of polyethylene under the deck.
You can buy one here on Amazon if you cannot find it at your local dealer: