What we have done previously to achieve such quality in a relatively static image is to MODEL the steam shape as a mesh, then convert to particles using PRT Volume, apply some KCMs to “eat away” particles based on a Noise Function and or Map based on their SignedDistance channel and render as Voxels. The result is a cloud-looking structure that is absolutely controllable in shape and can be fine-tweaked with the KCMs and maps.
Here is a popular example:
Here is what it was made from:
If you are interested, we can try to help you get something similar working for your setup…