Nothing much to be gained fighting the fire by air at night, from a risk vs reward standpoint. Wildfire behavior and activity is generally reduced at night anyway, making further defensive ground firefighting operations more feasible and effective, such as control line construction by personnel or tractors, and the beginning of slow burnout operations anchored to those and projecting inward towards the fire also at a slow pace. A fixed wing, or even a helicopter, isn’t going to accomplish much when compared to the high risk of undertaking aerial suppression operations at night. Sure, being the first guy to undertake them is cool and has some bragging rights in the aerial firefighting community; but is mostly impractical.
With all due respect, I think you're missing some really important points here. If you think of fighting fire as warfare, there are many positive tactical advantages to be gained by fighting at night:
1. Winds are usually much lower.
2. Temps are usually much lower.
3. Fire intensity is usually much lower.
4. With good IR, visibility of target is usually MUCH more acute.
5. The heat targets are usually much more confined and defined.
6. It's easier to hit ambiguous/blended targets when they are more clearly differentiated from their background environs.
7. There is less turbulence/ mountain wave/ nutball wind at night.
8. There is less "other stuff going on in the skies and on the comms" at night.
9. Night is calm. Night is peaceful.
High stress performance is always enhanced by beta and gamma... resulting from calm and focus and lack of distraction. The conditions defining "Nighttime" damned near
define the set of external conditions conducive to eliciting the desired high-performance set of internal brainwaves.
So, yeah, as opposed to your "nothing much", I'd argue there is actually "quite a lot" to be gained from night ops.
All that said... all that presumes that artificially fighting fires at all is any kind of good idea.