I have a 2008 R2 64bit Cluster file servers ran out of drive letters having issues adding more clustered file shares with mount points

I have 2 nodes in a cluster-

The cluster is called NAS

2 resources in there NASFS1 and NASFS2

I have set the prefered owner of NASFS1 to Node1 and NASFS2 to Node2

Each resource hosts a number of fileshares-  Basically all the drive letters are taken- 

I now have to create mount points

To do that on my SAN I create the LUN associate it to the cluster and then go to Disk Man on one server bring it online initialize and name it-  I then instead of assigning a drive letter create a mount point-  I have tried using a clustered drive with a drive letter (let's say drive M) and put the mount point there --> then create a dependency for that Mount point to initialize the mapped drive M has initialized.  It works until I fail over then it is assigned a mapped drive letter- 

I am kind of lost-   What is the best way to accomplish this-  Any help would be appreciated.

How should I do this ideally?