I'm trying to figure out how one manages 24 and 48 hour prints without potentially setting the house on fire.

As far as I am aware, no FDM 3D printer is safe to run unattended, overnight without supervision. I know there are ways to make things safer, with various interlocks, fire suppression items (like those kitchen vent-hood pucks), cameras for monitoring, etc. But I still wouldn't trust just letting something like that run.

I've yet to do anything with 3D printing, so maybe I am just out of the loop on this. I do know that software and hardware has come far enough to allow for print stop/re-starting (such as when reloading filament in the middle of a large job). Maybe that's how these long prints are done without the danger?