Mission plan doesn't allow negative gimbal pitch angles

Hi,

I currently have a SIYI A8 Mini gimbal camera that I have mounted horizontally on my quadplane which I want to use to test basic mapping capabilities. The gimbal pitch angle range is from -90 to 25 degrees where forward is 0. I want to fly a mission plan where the camera is constantly pointing downwards at -90 degrees, however under the camera category in the mission plan it prevents a negative pitch angle saying that the value must be within 0 and 90. The gimbal is using MAVLink Gimbal protocol V2 over UART for communication with my FC running PX4 1.16.

I can’t think of an intuitive work around for this and I don’t see why a negative gimbal angle wouldn’t be allowed. Any help would be appreciated, thank you!