But sitting in a field with only the camera's lcd screen to check, what should I have done to get the shutter speed and exposure right at the time?

1. Check your histogram: It will tell you the distribution of light and dark pixels (very basically speaking, check histogram) if you have only one peak at the highlights, you know that the image is overexposed without looking at the image.
2. Auto Exposure Bracketing (AEB): Just take 3 exposures each time you take an image. This gives you the choice to pick the right one when you are back at home.
3. Spot metering: let you meter determine the exposure on a very limited part of the image. This reduces the influence of a possibly bright or dark background on the exposure. Point the spot metering area at the subject, recompose and click. If I'm not mistaken, the 550D does have spot metering. If you have a camera that doesn't or you don't want to switch metering modes, you could also fill the frame with something that's roughly as bright as the subject is. This way, you don't have to guess a hard number for the compensation. Is this +1? or +2? You can visually determine what the camera should automatically expose for. yeah, that aircraft next to me is as bright as the one I want to photograph over there, but this one is so close, I can fill the frame without any sky in the background that throws the meter reading off
4. Post processing: Don't try to make perfect images in camera, just make sure you remain within the bounds of what you can fix in post. Even in film days people tweaked the hell out of their negatives. Changing lighting environments can be a demanding challenge. Don't get too upset about exposures that aren't perfect. You're there to enjoy the show, too.