Kayak camping is a lot of fun, especially if you can get out to remote areas where the crowds and powerboats can't reach. I do that often, but mostly in coastal areas so a hammock, while nice, is not usually the best option due to lack of suitable trees on barrier island beaches. I do like the looks of those Hennessy Safari Deluxe hammocks though so may have to add one to my gear in case there are trees! Since my kayak is a large expedition sea kayak I can carry lots of gear eventhough I still chose to travel light if possible.
I have two tents that I use. A Eureka Backcountry 1 is good for most conditions if going solo, is not too expensive and is fairly compact/light. The best for compact, light and quick setup with a little more room is the Tarptent Cloudburst 2. They are not exactly cheap but are really good quality tents.
The second most important thing is my Thermarest self inflating matress. The ground seems a lot harder and colder now than it did when I was younger, even in soft sand. Since I'm mostly coastal camping in the warm south, I usually only take a couple or three Space Brand All Weather blankets, the heavier poly tarp type not the thin mylar survival type, rather than a sleeping bag. You get between two of those on top of a Thermarest in a good tent and you will stay plenty warm even down to the 30s. Plus they can be used as a rain tarp, hypothermia recovery, even emergency shelter if needed. Even better, since they are poly there are no issues if they get wet, just shake them in the wind and they are dry in no time.
Whatever you choose, makes sure it will all fit in a lightweight waterproof bag like the SealLine ones. No kayak storage compartment is waterproof no matter what the manufacturer claims, they will all get wet in extreme conditions. Plus they make a good headrest when filled with air or clothes and sealed. Here's a tip...put the bag in your kayak's storage compartment first, put your stuff in it, then seal the bag shut. A lot easier to do that way.
Have fun! Kayak camping adds a whole new dimension that sometimes more than just enhances the sport. I've had a few times where I spent the day battling Beaufort force 5+ conditions in 3-4 foot waves on open water and am glad my gear is able to provide some evening comfort!