A practical option is to use a 3D sun-planning tool such as TPE 3D. It can visualize light and shadow across terrain, which makes it easier to see how mountains and other landforms may affect a landscape at a given time.

That said, these tools are limited by their underlying map and elevation data. They generally won’t account well for smaller or temporary obstacles such as trees, buildings, or other objects not represented in the 3D model.

So the best approach is usually:

• use TPE/PhotoPills/Google Earth to plan sun direction and terrain shadowing,
• use a 3D view when available to preview how the scene may be lit,
• and expect some uncertainty from unmodeled obstacles and real-world conditions.

In short: yes, 3D planning tools can help a lot with terrain-based lighting, but they won’t perfectly predict every shadow in the final scene.