"I imagine a prop (say, a ball or a ship) bouncing not from a surface, but immersing itself into it" Aha! Interesting idea. In fact, this terrain-following method would do it with very little change. It's just a matter of putting the "wheels" or surface sensors halfway up the side of the boat, instead of below the hull. And yes, the boat could move with the water when a wave deformer is active. I think I'll work on this first, because it's such a small variation.

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