I can't deny it is a possibility but in that scenario everything is down to the last second. If Jane had been just a few seconds earlier she might have seen Madeleine being handed out the window. That is pretty dramatic that the abductors would strike while Gerry and Jez were talking in the street. Very daring IMO.
To walk across the road when there were 3 people potentially looking at him also seems like a mistake on part of the abductors.
Why wasn't the getaway car right in the carpark next to the McCann apartment.
So what does the second person in the apartment do? Jane could pop out at any time and Jez and Gerry are talking.
The people who I am thinking of, have a motto, "HIDDEN IN PLAIN SIGHT"
This means hide something a couple of corners away ... and nobody associates the first place with the second place.
So hide the getaway vehicle on the little car park opposite Tapas Reception, then pick up two corners away outside the front of 5a, [but not at the actual drive in entrance .... more likely nearer to Jane Tanner corner, where the wall is very high.]
Except where delving very deep, there would be nothing to link these two places. Thus, "Hidden in plain sight ". A right corner followed by a left corner. A trip of only about 75 metres, and both places invisible to someone walking along Rua Dr Francisco Gentil Martins, except when actually in line with either the first, or second place. Also invisible to anyone looking out of the windows of block 5
It would have been a dangerous thing to do, to have pulled up in front of 5a window, because had anyone seen Madeleine being taken from 5a, then they would have made note of the vehicle Reg. Number.
For someone (the abductor) carrying a little girl to get into a vehicle, in the street, would not have been suspicious at the precise moment of abduction, because the two happenings would not connect (instantly). So no number would have been taken.
I truly (at a number of levels with apparant links) think that the getaway vehicle was parked on the small parking area opposite the Tapas reception. HIDDEN IN PLAIN SIGHT
Only my thoughts.