Non-MAVLINK Autopilot

I’m attempting integrate with QGC an autopilot that doesn’t use mavlink (ROSflight, uses ROS). I’ll need to convert the ROS messages into MAVLINK messages at some point, but for now I am just trying to generate MAVLINK messages to get QGC working minimally. For example, I can use MATLAB’s UAV Toolbox to broadcast a heartbeat and transfer basic params, such that QGC shows that it is connected and ready to fly.

I am having trouble figuring out what are the minimum MAVLINK messages I need to get a quadrotor image to pop up on QGC. Does anyone have any tips or ideas for me? Or any other information for generating MAVLINK messages with a script that I can later integrate with the ROS autopilot messages? If this is the wrong place to ask, let me know.