Excuse me if I missed something in this thread - I didn't read every post, but skimmed through it, but ...

It sounds like you're planning on stowing some (all?) of this gear in the kayak, but what happens if you are separated from the kayak?

I recently watch an episode of "I Shouldn't Be Alive" where a father and son went rafting on a river that unknown to them was not yet free of ice. They hit ice, got dumped out of the raft, never saw the raft again, managed to get to shore, and once on land had nothing but a fixed blade knife and a lighter. They managed to get a fire going and warm up enough to survive the night inside a debris shelter. The son (an MD adult with kids) left the father behind, took the only pair of shoes they had (the others were lost in the dump) and hiked to a major river where he waited hoping to be spotted by a plane - it worked, but they would not have made it another day or two.

Similar stuff can happen while backpacking (though many backpackers will get almost violent insisting that it can't happen and that a survival kit is a waste of weight). Imagine heading away from camp at night to dig a cat-hole and you get disoriented on the way back to camp. You're now spending a night in the woods without your primary gear. Hopefully you can find your camp the next day.

With that in mind, I have a few thoughts:

1. Have on your person at all times (imagine getting dumped unexpectedly and having to swim away from your kayak) sufficient gear to survive until help comes.

I'll second Leigh's advice on starting with one of Doug's PSP kits, tuck in a few extra critical components (LED light, mini Bic lighter, a few Micropur tablets), add a knife, some kind of liter-sized water container (HD ziplock bag), simple first aid kit (gauze pads, antibiotic, band aids), and some kind of shelter (very large trash bags, plastic sheets, ...). Keep it small enough to carry on your body.

2. Make sure you've given someone information such that they will miss you and send someone to look for you. Without that, it could be a loooong time before someone comes a lookin'.

3. Seriously consider saving up the money to add a PLB to your kit. It can quickly and easily turn a multi-day agonizing wait hoping for rescue into a few hours (?) of waiting for a sure rescue. Don't underestimate its value. These days a really nice PLB costs no more than a mapping GPS.

And again, the PLB does no good floating down the river without you. Put it on your person with your survival kit. I recently came across a video by Doug Ritter where he said the three most important things you can carry are a knife, a PSP-like kit with some extra add-ins, and a PLB.