I have messed up my back so bad a few years ago that I couldn't even stand or sit on a couch or normal chair for very long without pain for over a year afterwards. Fortunately I got better after a slow recovery but it never fully went away.
I sit at a desk for most of the day so solutions had to be explored. I've tried many things during that time. I've found out that what worked best was to be sitting with my legs not fully at 90 degrees with my body and my back held vertically, supported only by my core muscles.
Exercise balls worked fine if you sit more on the front edge of it, but you have to resist the urge of moving around and bouncing on it because that will absolutely wreck your back.
I've settled on a kneeling chair without a back support. The one I have you can adjust the angle so you can decide how much of your weight is on your knees and how much is on your butt.
Both of these require an adjustment period to get your core muscles used to be engaged for so long. Stretching your quads and hamstrings to gain more hip mobility so you can sit with your legs at 90 degrees without having to tilt your hip back and stand without tilting it forward helped a lot too.
The saddle chair does look like it would help too I might try it one day.
