We had a similar Flexsteel torture rack in our previous Fleetwood that we replaced with a recliner sofa. The only difficulty we had in removing the old sofa was the corner unit. I had to take the upholstery off the plywood backing and cut the plywood back from the unit. It then fit through the door. I did reassemble the corner unit in order to offer it for sale although after advertising it for months without response I donated it to get it out of the garage and out of my sight. I don't know if your sofa is Flexsteel, but if you search the Fleetwood threads, Sarah H did a great writeup. The new recliner sofa was easy to get in as the backs are separate pieces and easily unbolt to remove them.
As far as the height of the back blocking the window, my wife had the same concerns, however after sitting on the new sofa for about 5 minutes it no longer mattered to her. I did cut down the side window valances in order to move the sofa closer to the wall as the new sofa was a wall hugger and did not need to be that far from the wall. Do it, you won't regret it.
2018 Tiffin Allegro RED 33AA, 2016 Wrangler, 2013 Harley Electraglide