You'd have to either use volumetrics like vdb or something. Sadly Skytracer wont work together with Physical Sky. That would be too easy..lol.
VDB not recommended for larger skyscapes, just use the primitive item volumetrics, you need several items to cover distance clouds and middle and foreground, you can use large scale items, and smaller as well and make them more cluster like and manage within null master groups, not as easy as infinite clouds..but I have told them too many times they need to implement the infinite volume cloud layer.
You can also use textured environement together with physical sky and try to make some fast easy clouds that way, takes a bit more work and not physicly realistic in terms of lighting and shading, just fake volume hack feel with gradients.
Ozone from vue and ogo taiki was decent, but isn´t compatible anymore..and further more not developed, so the range of options have decreased.