If the doors were where you suggest, shouldn't we have seen something like this?
That would depend on the framing, now wouldn't it? And that in turn would depend on the perspective of the forced-perspective set. I could see the control booths being framed out left and right, leaving only the inside of the doors - and if that were out of focus, the seams might not show.
Also, we might postulate that the flight deck features at least two turntables, one at the observed location and another further forward. That'd improve the logistics of the supposed two-deck arrangement, as well as improving our chances of finding suitable angles. A shuttle on the putative forward turntable would probably be visible through a forward wall doorway in a fashion that would frame out the control booths...