Don't know if this will help, but we found an ottoman at Walmart that made a world of difference in our 23SS. I think being able to get out feet up was the problem and for a nominal price, this fixed it and we were fine. Room for 4 feet on one ottoman. Ours had a storage area inside where we kept all the doggie stuff. Did double duty for around $30 or so.
To try to remove and replace the sofa in the 23SS, would leave a number of holes in the flooring and you'd likely not be happy with those holes. My cousin and DH were considering replacing the sofa in their KZ, but found the only ones that would fit were Lazy Boy and pretty $$$.
In our new TT, I honestly believe they set the swivel rockers in the middle of the unit and built around it. I cannot see any way to maneuver them around to get in/out the door. bikendan has a point that you may be able to put something in through the bunkend. Personal opinion is that I'd check into an ottoman or similar before starting on a project that could turn into a real nightmare. Good luck.