Glad to hear you are making some progress! It's much easier getting in & out of a Box with the top down, can you park it inside with top down? The sport seats are more supportive in lower lumbar area, but have 1/2" higher side bolsters.
Over the last 15 yrs I have driven a lot of vehicles, you can judge how well the seat fits you by how little you want to move around when it's a good fit. If it's not a good fit you are constantly squirming around trying to improve your position. Best seat I have found for me is a 2013 up Lexus IS, got one for a loaner, sat down & never moved the whole time I drove it, I was amazed. Yoga has made my back better than it was 10yrs ago!
Also reflexology massage does wonders for getting things in line too.