But low light performance and interchangeable lenses are almost diametrically opposed to what what they're doing. You need a large sensor and lens to get good low light performance (which makes it bigger) and so would the mechanism on an interchangeable lens. Further the interchangeable lenses are just additional parts to fail when you're bouncing around on your kayak trip.
If you just want portability, you probably want something more like a micro 4/3s camera. I assume they can capture video but would almost certainly be more fit for the job.