Mess with the exposure on the camera and consider adding a couple ghost lights.
The way you make a ghost light is you create a primitive and give it an emissive Iray surface then cut the oppacity down to .00001%
It'll still cast light and shadow but be functionally invisible. Then just dick around with its luxuriance, size, and position.
Edit:
Seems you figured it out on your own.
Ghost lights have been a thing in daz since ray was introduced. They do a relatively good job of things.
I actually use them for a lot of illumination duties, esp when converting items to cast light that were not originally iray. A lot of those have defuse maps that make them look illuminated but when you give them iray emission, they turn into a glowing colored mess.
Way around that is to make the part just emissive enough that it glows the way you like, then create a geoshell of the object, and have the surface that emits light on the geoshell have a ghost light.