I like this one very much. Congrats!
And I love this place, too. Another view (I hope you do not mind!): http://www.monoart.de/section348020.html
You are a very prolific and versatile photographer.
To avoid the white banding between the sand dune and the burned-in sky, let the masking card move into the sand dune. The additional exposure will be hard to see, and the sky will be evenly burned in right to the dune.
Very interesting image.