When kayaking, you can't carry everything that you would really want. Sure, you can bring a life jacket and some warm or cool clothes, depending on the weather. You can bring some little devices and some food for a long or even short trip....but you can't bring everything so you have to improvise with the tools you already have.
Some equipment that you bring can only be used for it's sole purpose. It's not like you can use a water bottle as a flotation device or a heart monitor and paddle. What you can use as a multi-tool is your paddle. Most paddles come apart in the middle so you have two paddles to use. I have used my paddle as an arm to help lift or bring things closer to me. I have also used it as an anchor and also as a plate for food. When I was on the Wisconsin River, I disassembled my paddle and turned it into an anchor when I was taking a break on the water. It became very helpful and hand because then I could get in and out of the kayak without having to worry about getting the boat off of shore.
The main point to this article is to get you thinking of different ways to use what you have for other purposes to achieve a light weight trip. MacGyver was my childhood hero....so that might have something to do with it.