TMP1075: How to do DGK package PCB layout?

Hi team,

My customer used TMP1075DGK in their system but they would like to know how to do PCB layout because there is no thermal pad for this package. And we see there is ref. layout in datasheet. see below picture.

So my customer is asking do they need to directly connect this thermal plane(between our device and heat source) to whole system ground plane? or just use few vias, ex: 1 via or 2 vias connected to system ground plane?

Thanks