The Kirk Plates have a nice cutout that you can just get a finger in to open the door and that with the left side of the plate against the rubber of the body on the cam as it should be. If you do have large fingers it might be more problematic but I do use the USB connector as my card reader was an old USB1. Fortunately someone is gifting me a new Lexar UDMA FW800 reader soon so will be a non issue though if seeking a L-bracket, give Kirk a look.
John
John