I didn't see the original picture, but if there are no buildings invoved, I'm sure you can use any proportion, since hills and mountains can be as large or as small as you like- just a thought.
The copy of pics i have, they do have a couple of buildings on them. I will try to make the buildings look further back in distance. I think i will be able to something like that in Photoshop. Photoshop is an amazing graphics program.