Frank Proctor worked with Unity Tactical to come up with this mount for Streamlite Protac 1L. This also works with Streamlight Protac 2L and Surefire E series lights.
It is a very skinny mount using only one slot
Price: $89.95
http://www.wayofthegun.us/plm-proctor-light-mount/
From: Unity Tactical via Soldier Systems