OnTrigger needs a concave mesh due to preserving IndexTriangles

I created a simple model of 18 faces that I created in sketchup and made a fbx through blender (A thin pentagon tile with slightly peaked roof). I did this so I can have very simple easy to index triangles that can be referenced with a RaycastHit object.

My script reacts to specific traingleIndexes.
The goal of this is for the script to react differently to which part of the pentagon tile is hit.

Other objects need to know if the pentagon collides with the other objects.
Marking the collider as convex will destroy the triangleIndex of the mesh I need to use.
I need the precision of the mesh collider because these tiles can be placed very close to each other.

A combination of box colliders can be precisely shaped to represent my pentagon tile, but I would like to keep the hierarchy as simple (less children), because I want to be able to use the heriarchy as a tree sort to see if tiles are places in specific arrangements.

I solved the issue.

pentagon Tile:
Mesh Collider convex [unchecked]
No rigidbody
No primative colliders needed to approximate shape: I used the mesh from the fbx sketchup

Mesh Collider: convex [checked]
Rigidbody:IsKinematic [checked]
This object is not needing the preserved triangleIndexes

script on otherObject

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class SelectorTileScript : MonoBehaviour {
    private void OnTriggerEnter(Collider other) {