As long as your plant has everything it needs, its roots are very unlikely to start rotting. It's unhealthy/dead roots that rot.
I've never monitored my temperature or done anything but pump air into DWC tanks (no water pumps). Even with accidental light leaks, it just creates a nice green paint around the firm healthy roots, which is easily rinsed off, light leak fixed. It never actually causes the roots to rot.
My experience leads me to conclude that root rot comes from the roots, not from the water. Unhealthy roots lose their firmness and become starchy. That starch leaks out like a white slime and becomes infected.
The only time I ever get root rot is when I'm lazy and forget to throw the roots away after harvesting. They rot after dying, not before.