In the tank trucks you see driving down the road. The tanks are compartmented and has dampers Like large fabric pillows that damp the sloshing of fluids. Generally the attempt is to keep a compartment absolutly full to reduce the change in balance caused sloshing around. I don't have a clue how one would add that idea to a yak. Still its a design thought

When I was in the merchant Marines, Tankers used to get stability by building wide and deep. Perhaps a boat that had a deeper draft. Something that got more stable as you added the water columb. A boat shaped in cross section more like a pear, or even triangular with the corners rounded off. Fat down below and thinner up top. Then make your live well conical to put more water on the bottom then on the top. It would probobly be pretty darn unstable unless you had the live well filled. So it would be a one function boat.

Mere muzings
Enjoy the problem
!RUSS