Align camera to plane/quad boundaries

I'd like to align my orthographic MainCamera, so that a ground plane/quad in my scene always fills up the horizontal screen space.
At the moment I try to get the boundaries of the plane collider and move the camera in/out until the bounds are nearest to the edge of the screen.
Since it's a mobile game, the aspect ratio and the screen size could be everything.

This seems to be a bit cumbersome, any Ideas how I could achieve the same effect with a more elegant solution?

 

Years without an answer?

Throw this script on your quad and center it on the screen.

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class ScreenScaledQuad : MonoBehaviour {
5.  
6.     public ScreenScaleMode scaleMode = ScreenScaleMode.ScaleToWidthAndHeight;
7.  
8.     public enum ScreenScaleMode
9.     {
10.         ScaleToWidthAndHeight,
11.         ScaleToWidthOnly,
12.         ScaleToHeightOnly
13.     }
14.  
15.     // Update is called once per frame
16.     void Update ()
17.     {
18.         float quadDepth = Camera.main.transform.position.z - transform.position.z;
19.  
20.         Vector3 tr = Camera.main.ViewportToWorldPoint(new Vector3(1, 1, quadDepth));
21.         Vector3 tl = Camera.main.ViewportToWorldPoint(new Vector3(0, 1, quadDepth));
22.  
23.         // DEFAULT: Scale To Width & Height
24.         float aspectRatio = transform.localScale.y / transform.localScale.x;
25.         float widthScale = (tl.x-tr.x);
26.         float heightScale = widthScale;
27.  
28.         // WIDTH ONLY?
29.         if(scaleMode == ScreenScaleMode.ScaleToWidthOnly)
30.         {
31.             heightScale = widthScale * aspectRatio;
32.         }
33.  
34.         // HEIGHT ONLY?
35.         else if(scaleMode == ScreenScaleMode.ScaleToHeightOnly)
36.         {
37.             widthScale = heightScale / aspectRatio;
38.         }
39.  
40.         transform.localScale = new Vector3(widthScale,heightScale,1);
41.  
42.  
43.     }
44. }
45.  

 

Still not working