Btw: Do you already have Experiences about Steering Behaviors and dynamical obstacle avoidance?
E.g. Ogrecrowd is a project which might be worth taking a look at.
Essentially I mean that the "Follow a Path" Behavior somewhat uses the Avoidance Behavior to not crash into a) Dynamical Objects and b) The World due to Avoidance.
a) Essentially means that we have a "colission radius" and when an npc/car is within this radius we use that as obstacle to avoid, but:
b) Our Steering Behaviors alter the curves you walk. What happens, when those lead you against a wall? I thought about using some mathematics to detect the holes in the poly-navmesh and then somehow filling it with boxes but that feels problematic, maybe there is already something from the recast side?