For improved ergonomics, add the Olympus ECG-2 External Metal Grip to your OM-D E-M5 Mark II. It not only provides a sturdier way to hold the camera, but also doubles as an Arca-type compatible L-bracket. With dovetail grooves on both the horizontal and vertical plates, you can quickly change between portrait and landscape modes.
Both the grip and vertical plate are removable, so that you can use the horizontal plate on its own as a long quick-release plate. The ECG-2 is designed to allow access to the camera's battery and side ports, and a hex key is included for the mounting screw and set screws.