Your modification looks good Mathew. I think that some items, such as L-Brackets, should be regarded as consumables and that tailoring them to fit ones cameras and equipment is fair game.
An alternative to your straight cut all the way through the bottom of the plate would be to cut the front rail and the middle portion of the plate the same as you have done and then to preserve the rear rail as it doesn't interfere with the opening of battery door. I concede however that this does make for a more complex cutting procedure.
True, I could have done that, especially because I was side milling, but I don't think there's a lot of point to a lone rail on this kind of mount, and the pad is quite strong enough with the whole piece gone.
