I took the couch out of my '00 Kountry Star and replaced it with 3 forward-facing captain's chair from a van conversion. People were getting car sick riding sideways. It couldn't have been my driving, as the new seating arrangement helped the problem.
Anyway, the couch came loose with the removal of about 6 screws about 3" long. These were easier to get to after unbolting the armrest end panels. That also made it easier to get out the door. Silly point, but be sure to remove the cushions and mattress before trying to get it out.
I used 1/2" carriage bolts with large steel square-hole washers under the floor to hold the new seats in. If I ever had a problem, I didn't want to get hit in the head with a flying seat. (When I did have a problem, the seats bent but they didn't come loose, so it worked.)
Anyway, your couch should come out through the door. BTW, what will you do with the old couch. I could use one in my new ride.