I've changed where I inject the smoke / from (above the camera, rather than the camera left side) and have made some changes to my workflow to create a more subtle horizontal surface. I am going to sit on this for a few hours and tweak it a bit more before making a print.
I haven't been using Photoshop's pen tool to make selections lately, but it has worked out well for this one. It has a long and challenging learning curve, but once mastered, you can do things that just don't work well enough with some of the other tools.