NAV Mesh Constraint: Is there a way to vertex paint valid regions for pawn to move or tranport to?

First time poster,

My project has several environments where I need to prevent the pawn from navigating to/through certain places.
I’m aware of the Navagation Mesh workflow, that has some of the attibutes I seek, however my very organic/complex/non-rectangular set isn’t suited at all for rectangular Nav Meshes.
I’m also not wanting to have to model lots of collision objects to constrain movement in that way.
I’m hoping to prevent movement through walls, or getting overly close to areas with issues I want to keep them away from.

What I’m hoping exists, or could be made to exist, would be a method that lets me use Nav Mesh with a painted Vertex Map for constraining movement or transport to, which
reads a vertex texture value from the mesh surface. So I paint alpha on a large rectangular mesh where it is legal to move or transport to and in my testing for a legal move,
I test whether we Hit a Nav Mesh AND if the Alpha channel at that lookup point is also “On” / “White” indicating its fine to move or transport there.

Is there a way to do this ?