Then I will wait for your update with the gradual sea state change.
The other thing I am trying right now is having a seadoo acting properly with the water surface. Turns out the high linear damping when submerged makes it instantly stop when I stop accelerating (force applied).
Might be worth avoiding the object buoyancy-hopping out of the water by implementing a opposite force proportional to z-speed, i.e. water push-away resistance, instead of simply upping the linear damping.