To get a better idea of how the mountains will look, I used the new landscape blueprint brushes to create some basic shapes. While this is a quick and easy way to modify the landscape, I have to say that the performance on my laptop was really poor. After using three layers of the new landscape system, I decided to export the heightmap and merge all the layers together to improve the performance. With a better desktop computer this step may not be necessary, but I really needed to improve my editor speed.

This is the resulting heightmap:

I really like the perspective of my second reference, so I am going to adjust my UE4 cinema camera to macht that one, using a 35mm focal length that I think will be similar to the one used to capture the image. Using a UE4 landscape, I made a quick blockout, using the landscape editor and one spline. I created a basic landscape material just to see the landscape better.