Low clouds over desert

Thought I'd try a desert landscape but done slightly differently. Instead of a height map or displacement or terrain generation, I used Maya's BOSS spectral wave simulation to generate a seascape and then shaded it to look like a desert. So you're actually seeing waves here, not sand dunes! I guess in some ways the physics are probably (very) slightly similar.
The other thing I wanted to play with was volumetric clouds. The setup is actually really straightforward: 3D Maya cloud texture -> Arnold standard volume. By scaling the 3D texture placement gizmo you can quickly set the size of the clouds. But to get it rendering like actual clouds you have to increase the volume ray depth to something like 6 or above. And that massively increases render times.