8TB, once processed the default plots are 100GB and can live on slower media. While being created, they require 240GB of temp space on preferably faster media.

That's where the SSD problem comes from, during creation the 240GB is thrashed, it is reused for every plot made. So an 8TB storage for finished plots implies 80 finished 100GB plots, which implies 80 x 240GB of thrashing on the SSD to produce them.