This is a design problem. We want to use the standard pack (flight controller, sensors, etc) to build a fixed-wing drone but we are worried about the size of the drone. Is there a size limit (span) that a classic configuration of sensors, controller can make fly well in autopilot?
There’s a YouTube demo someplace of an ArduPilot SITL + flight sim connection to a 747 model. I’d say the limit is only constrained by your imagination!