I am working on the same basic composition. In this one I am using colors more close to nature. I have angled the horizon and it works for me. All along I have tried to be accurate with the horizon line and here it seems to work great.
I am using my palette knives only and some of the interesting effects are from adding medium to it so that the paint isn't so thick. Then I lightly touch the surface at an angle with the effect showing on top. I will be using this again.