I had compression fractures of multiple vertebrae two years ago and have dealt with a lot of back pain over time. While some things helped for a while (like a small inflatable pillow behind the small of my back) what helped me the most long-term was a wedge cushion with a cutout in it:
https://www.amazon.com/Car-Seat-Cushion-Strap-Wheelchairs/dp/B00Q5HXQ9O
That's one of the pricier ones but it helped me a lot. I went from getting sore after two hours to being able to handle at least 2-3x that. That said, I'm short, so a little extra seat height was welcome.
I'm short. I didn't raise the seat but I bought a seat booster/cushion. This is what I bought but it's no longer available. https://www.amazon.com/gp/product/B00Q5HXQ9O/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
There are a plethora of seat cushions like that on amazon.