This downwash is just what a fire wants. It is not good to have the ground crew cursing your name because you made the fire worse. Downwash can also be a hazard while landing to or hovering over a burnt out area. This can cause a brown out condition where the pilot loses all reference to the outside world. And finally, be aware of your own limitations.
Pilot fatigue causes inattention.
Don't over extend yourself just to make a buck. That extra hundred dollars isn't' worth a life or the cost of a new aircraft. Mostly we notice when it hurts. The very conditions that caused the fire to start, now keep it going. Fires can also create their own weather pattern.