Hi guys, I just registered on this forum to share a solution with you that someone pointed out to me on Steam.
When you are the gunner/copilot in multicrew, the controls for the camera are bound to the regular Pitch and Roll channels. In multicrew, these automatically become the slew controls for the camera. So under Axis Assign, just have the Pitch and Roll axes set up as normal, leave the Slew Left/Right and Slew Up/Down fields empty, and then you should be able to control the camera with the joystick.