By the way: If you haven't already done so, put a small Carabiner in your camera bag when you travel afield. You can use it to link a D-ring on your camera bag with one of the base supports on your light stand to make an impromptu sandbag for a little more stability in the wind.
Speed Light Position: When using an umbrella, it is always best to position the speed light as close to the umbrella shaft as possible. Unfortunately, most umbrella brackets use the speed light's hot shoe as the point of attachment, putting the light source high above the umbrella shaft. To compensate, umbrella bracket manufacturers drill the mounting hole at an angle so the line of site for the speed light intersects the shaft were it meets the umbrella. This works so long as there is vertical "space" for the speed light, as there would be in an umbrella.