Collision Detection with edges of planes

So, we’re making a 2D platformer that has a mechanic that requires us to use planes as our platforms. The planes have to be rotated so they are facing the screen(so player can see the image). The player is a rigidbody. And the platforms are planes with a mesh collider set to a plane. We are trying to get the player to collide with the edge of the plane, not with the one face that is collidable because that is facing towards the player so that they can see it. Normally in unity the plane is only collidable only on one face and you can pass through the plane from the other side and edges. And we want to be able to make those edges collide with the player. If anyone has any ideas it would be greatly appreciated, we are kinda at out whits end…

Why not just use boxes and box colliders? you see one side of the box, and player collides with the edges.