So I decided to try out using light planes in lieu of a heliodon. Actually, I created a segmented light dome, with each segment a different material so I could assign separate shaders (neon glass) to each, and get a directional light. I selected a background photo with no direct sunlight, as an example of the lighting condition I wanted to replicate in Artlantis. The resulting images are attached (not intended to be 'final', just a comparison of lighting).
The "Comparison Heliodon" image is using the Artlantis heliodon, and trying to reduce the sun light settings as much as possible to replicate the lighting condition. It seems that the "Sun" adjustment doesn't do that much to the lighting of the model. But the attached image is the best I could do.
The "Comparison Light Dome" image was prepared using the light dome described above. It took a bit of time to get the adjustments right, but the result is more consistent with the lighting conditions in the background image. So it works, though the process lacks the simplicity of most Artlantis workflows.