I use one like this.
https://www.amazon.com/Antlu-Massage...kle_mcd_asin_0
I love it. You don't need to worry about lumbar support, because you are sitting upright on this stool. And it puts your back in a very comfortable position. Your abdominal muscles learn to be your back support. I have one of these at my sit down longarm, and want a second one for my regular machine downstairs. Maybe Santa will bring me one?