We know that the Upper Western has had some sales into it, as there are people on this forum who bought into it when it went on sale a couple of weeks back.
In addition, would you think, if the entire section was empty, they'd start selling from around the 20-30 metre lines? They would of course put the middle bays on sale first, as these are both the ones which are most highly desired, and as well would appear in the majority of reverse shots on TV, as such we can assume at least the first half of these Bays most likely have people in them (they may leave the back of these Bays empty as that's less visible)
As for the Bays which are on-sale, if you scroll over the 'Grey' seats, you will see they will either show up with a 'overlay' of 'Sold Seat' or 'Unavailable Seat'.
Unavailable's are most likely seats still on hold, but Sold seats would be allocated in some manner. 83 definitely has a lot of seats in the Bay marked as Sold, versus 89, the far back rows look to be unavailable.
Seats Per Bay in this area is as follows:
81 - 168 (Assume 0)
82 - 469 (Assume 0)
83 - 421 (Around 80 Sold)
84 - 601 (Assume 300 Sold)
85 - 565 (Assume 280 Sold)
86 - 520 (Assume 260 Sold)
87 - 565 (Assume 280 Sold)
88 - 601 (Assume 300 Sold)
89 - 421 (Around 180 Sold)
90 - 469 (Assume 0)
91 - 168 (Assume 0)
So worse case, we'd be around 1,680 of the 4,968.... could be worse...