I have never pre flash but I can practice doing small prints on a cheap paper to see how it can helps.
On the sky there is no information. But if I can make it looks light gray instead of white it would be nicer.
I actually used a yellow filter to take this photograph, to give some contrast the greens and brown tones of the leaves and trees.
To be honest, I actually don't know how I could save the sky texture in a such contrasty scene.