If I'm not mistaken, the idea that she left at 12.40 is itself based on the supposition that the 12.45 diary entry was genuine. She had a 12.45 appointment, it's 5 minutes away ergo she left at 12.40. But what if it's not genuine? There was no clock in the office, nor any reason for anyone to notice what time she left, so why can't she have left Sturgis at 12.20 or 12.30 on her real errand?
This would allow her car to have been the one seen by WJ. This debunks both BW and DV, but it also debunks the entire 37SR narrative, because she was clearly never there.
So we now have absolutely no idea who she might have been with after she left the office. The supposed identikit pictures of Mr Kipper at 37SR depict, as DV has said, some random who has nothing to do with any of it.
The problem with the WJ sighting is that it doesn't look like she drove the car. It does look like someone abandoned the car in a hurry. This could have been because she pulled up behind someone she was meeting who was perhaps parked also, and got out of her car leaving it unlocked and not properly parked, expecting a brief conversation. She never returned to her own car even to lock it, nor did anyone else, yet somehow the seat got moved back.