Multi aisle commercial aircraft adopt a multi-door strategy rather than a single-huge door (see the A380 or the B747, both have two doors). This helps under the structural viewpoint: the presence of a door (cargo or passenger that might be) induces design problems that are amplified if the compartment has to be pressurised.
A door interrupts both Ribs and Longerons and weakens the overall aircraft structure. A huge door interrupts many more ribs than a small one and two small ones can be set apart from each other to have some continuous ribs between the two, restoring some rigidity.
The complex closure systems ensure that part of the stresses are carried by the door material, but it will never be perfectly transmitted as it would be without a door. As mentioned before, the stresses are heightened if the compartment is pressurised (as when passenger have to be transported).