I recently removed and reupholstered the couch in my 2003 SO. The task ahead is not difficult and the couch can be disassembled easily so one person can do the job. The pictures below may help alleviate your concerns.
The exposed frame (picture 1 w foam & upholstery removed) allows you to see the basic frame and hinge mechanism. There are four nuts which hold the back to the frame hinge (2 each side). Likewise, there are four nuts that hold the seat bottom to the hinge mechanism. The base frame has four screws that penetrate the floor. The front lower panel was separately screwed to the floor as well as the 'arm' sections.
The newly upholstered couch back is shown (pic 2) and you can see the two bolts protruding from the corner. These are the attachment points to the folding mechanism.
It is easiest to remove the entire assembly from the floor mounts, pull the couch away from the wall to access the back and remove the four nuts. One person can then take that upper piece out the door. The lower assembly does not not need to be disassembled for removal, but if weight is an issue for you, the bottom cushion can be removed from the base legs in the same manner.
"Good judgement comes from experience. Experience comes from bad judgment."
Sirs Gawain & Galahad
Air #48582, S/SO #003, WBCCI #4584