I had major fusion surgery a couple a years back. I had to mess with mine a while but have it right for me now. Best thing for me was raise legs up lean back some made a big difference

 

Have you tried to adjust the lumbar?

 

I'm a big guy, 5'10", 275 lbs. I've driven 11 1/2 hrs straight (CT to PA and right back, 5 1/2 hrs each way) in the SS and the only problem I had was a sore driver's knee. My back and arms were fine. I adjust the lumbar at least two-three times a month in mine, depending on how it feels to me. Just tweak your seat settings until you find something that's right for you.

Later
Allex

 

I had a problem with a sore back when I first got the car, so I took the car in to a shop and had the back of the seat lowered about 3 inches. No problem since I did that done and I actually have headroom now. Oh and as a bonus I can now see stoplights!