To do this she would need 10 shafts. Four shafts for the waffle area, four for the twill, and two more for the plain weave selvedges.
It is possible to weave plain weave hems on the above 8 shaft draft by tieing up two more treadles to achieve the plain weave. It is also possible to weave twill stripes in the weft by tieing up four more treadles to weave twill all across the cloth. With only 8 shafts you need to thead a point progression to get waffle on four shafts.
The effect of having a plain weave 'frame' would be, I think, to have the ends and selvedges 'ruffle'. Of course it would depend on your choice of yarn and density how much this would happen.
The higher the density, the less it would ruffle, I think, but until I wove a sample I would not know for sure.
I rather suspect that this textile has been woven on at least 10 shafts if there is a plain weave selvedge, possibly more. I wonder if the hems are basketweave rather than plain weave, but I can't tell for sure from the photo.