For anyone who is interested, here is my basic setup for recording while kayaking. The handmade rig is not pretty, but it is very functional, and most of the rig cannot be seen from outside the kayak. I have other cameras but rarely use them on days out on the water.
1: DJI Osmo Action Camera.
2: Ulanzi Quick Release Base ( one on each camera)
3: Insta360 Extendable Selfie Stick.
4: Homemade Polypipe Camera Rig.
5: Insta360 X3 Camera.
6: Insta360 (3 metre) Invisible Self Stick.
7: 20000 mAh Powerbank.
8: Intra360 X3 Remote Control.
9: Boya External Microphone.
I stow my 5-litre (essentials) dry sack in the middle of the camera rig, and other recording equipment such as my Rode wireless microphone and gorilla tripod are stowed away in my 15-litre dry sack along with my general kit for the day.