As you seem well aware, because your platform is moving, it's important to keep the shutter speed up to avoid motion blur. So I always use Shutter Priority with enough wiggle room in the overall Exposure Value to allow the aperture to do its thing. Generally speaking, this comes out to about 1/1000 shutter and ISO 100 on sunny days and 1/1000 to 1/800 and ISO 200 on cloudy, partly cloudy, or very cloudy (dark) days. I keep an eye on the aperture during the entire flight to make sure there is "wiggle room" in the exposure. If the aperture stays wide open the whole time (f/2.8), this leads me to believe that there may not be enough room in my exposure settings to allow for deep shadows or another light-changing anomalies. I like to see the aperture hover one click under f/2.8 (f/3.2 I believe), with the occasional "dip" into f/2.8 territory. Using this formula all my photos are property exposed, regardless of lighting conditions. And if you've ever mapped on a partly cloudy day, you know that exposure can be all over the map.
And FWIW, I never use Auto WB. The software I use doesn't allow me to "hard code" the WB, so I select either "Sunny" or "Cloudy." The WB doesn't have to be correct, but it DOES have to be consistent. Auto WB bounces back and forth from Sunny to Cloudy producing horrid results.
D