The search term you want to use to find a one cushion couch is "bench" cushion. Sam Moore furniture has a few.

Thanks for the tip! And I hadn't realized RH had an outdoor fabric option with their perennial fabrics. Just ordered some samples.

There are many manufacturers who offer design your own where you have a choice of arm style, seat cushion etc. There is also a new stain resistant fabric called Crypton that many are offering. Look at Henredon upholstery, Taylor King, Wesley Hall. For a mid line I think Bassett has a design your own program.

Thank you for the suggestions. I really appreciate it.

I know this is an old post, but did you find one? I'm looking for a similar style! The bench cushion worries me because of potential sagging and wrinkling. We have one main room as well--no formal living room. So we do our lounging, tv watching, and entertaining friends in this room. Looking for comfort but also style!

We bought the sven sofa from Article. I wanted to love it, but the back cushions get really saggy so I need to probably get foam inserts. The bench cushion shifts a bit, showing the darker fabric that doesn't match. Comfort for me is 4 stars. (Subjective, for sure.) I wish I would have returned it during the allowed window, but I think if I do foam inserts in the back cushions I'll like it a lot better. I have a different bench cushion sofa that I've had almost a decade that I bought second hand and I love it (5 stars for comfort). It just wasn't the size I needed for my living room. I hope you find something that works great for you!

Who made the second hand sofa? I would love to find a manufacturer who makes one that will hold its shape!

Room and Board has several bench cushion w/track arms https://www.roomandboard.com/catalog/living/sofas-and-loveseats