My own view Sadie is that the southern car park is overlooked by far too many properties.
Note the lamp standard where both GNR tracker dogs lost Madeleine's scent.
John you may be right. When we visited it was exceedingly quiet, and our visit was in high season. The Mccanns were there in low or shoulder season, so likely it was even quieter, but I acept what you are saying.
The building that I believe the Watcher was in, is the building to the extreme left of the image. I think that the gate is the first vertical orange line. That is the first very thin orange line. The getaway vehicle could have been pulled virtually up to that gate. Remember that Madeleine was not being transferred there; she was being picked up at the drive-in entrance to 5A on another street.
As there were two corners to go around, nobody in those little houses would have thought that someone getting into a van parked there was anything out of the ordinary. THe pick up, where things became suspicious to the inquisitive, was around two corners and well out of sight. Nothing to connect the man getting into a van with an abducted child.
A mundane event, a man just getting into his van and driving off. That is all.