A mobs hitbox in a boat will stick out, causing it to burn in lava

The bug

A mobs hitbox in a boat will stick out, causing it to burn in lava; expected the hitbox to shrink in size while in the sitting model.

How to reproduce

1. Place lava in a 1x1 hole.
2. Place down a boat, and push a zombie into it.
3. Steer the boat over the hole with lava.
   → Zombie starts burning