Keeping player object from climbing Mesh Collider Rocks

I know I could put up box colliders on the edges, but I'm trying to avoid that, since it'd likely take 5-6 hours (big level, maze of rocks, lots of non-striaght lines).

But when the player moves to the rock, it's able to climb steep angles. I have the physic material set to "0" for the rocks and higher for the player and "minimum" when they collider, so it should be "like ice", right? But still the player is able to climb.

Is there another way to do this to keep the player from climbing? Thanks!