Holy cow. I wish I'd seen this thread earlier. This is hands down the easiest way to get mountains exactly where you want them. The only suggestions and alterations I have, are that you should use a rough texture for the mountains that tiles seamlessly and is a neutral grey color so you can paint down textures on top of it to get the exact colors you want and blend it in with the map better.

A friend showed me their map they made using this technique and I was floored. I tried it and these mountains are so simple and easy to create and easy to alter. Just pattern stamp and erase as needed. This is a very interesting use of the bevel/contour/texture features.