Ouch.
You got me....
Too much RL mongering has precluded my own effort upon this very phenotype idea.
Although I positioned the PC into a kneeling stance the answer to your question can be resolved in Z axis placement of the boat/ tail mesh.
My own efforts progressed along a forced perspective notion.
The boat needs to sit upon the water properly. But the inside of the boat could be a mesh slightly higher than the hull of the boat (above the water line).
The intersection of the plane of the water and the interior of the boat cannot be avoided. But it can be hidden. Perhaps beneath gear inside the boat
Waves and /or bobbing of the boat will be seen within the hull.
The juxtaposition of the hull into the rock is a more complicated problem. It cannot be completely avoided. Like when a fighting character intersects with a wall or a door. However, editing the 2das under personal space is one method and the creation of scripted trigger areas (zones) can mitigate this issue.
My original intention was to create a white water river canoe pheno using special animated placeables for the river bank (see the mine cart video, and then look at how the skybox works in the overland travel microset, and then there is the animated ships and aircars (d20) which traverse upon splines)
Good work Quevy !!
Keep experimenting and you will get amazing results.
I have numerous similar projects just begging to be finished but recently I have had no time to concentrate upon them (sigh)
Long live Nwn