Topless - stage 4

I have started to paint in the bottom half of the picture trying to get the tonal values right for the design I have in mind. This picture is quite tricky as I want the lightest area to be the strip of orange sky with everything below it  kept to similar mid-to-dark values which means I am using colour in a tonal way; substituting a dark tone for instance with a rich purple instead of a grey or black. I want strong saturated colours with the pink building having a slight glow to it.....