I made it as thin as possible but it has to be a certain height to accommodate the post on the grip frame and the rail on the pops. It's about the same height as a standard dovetail rail-- CCM and the like.
I'd be happy to make one for anyone interested, but pm me any questions so we don't violate BST rules.
I diet milled it to remove most of the unnecessary material so it's pretty light.
Disregard the machine marks in the pocket, the only end mill I had small enough was in pretty bad shape.