When I bought my used RV last year, it had about 38000 miles on it. At an average of 45 mph, this calculates out to about 850 butt-hours in the drivers seat. Along with 20 year old Ford foam, the seat felt OK but not good.
After about an hour of driving I would have pains in my hips and going down my legs. Reaching under the seat, I could feel that the foam was compressing completely thus causing pressure points.
I thought about getting a $450 aftermarket seat or a local reupholstery job which would be a couple hundred.
After contemplating the situation for many butt-hours in the seat, it occured to me that this must be a common situation and I checked Amazon for the highest rated cushion.
Thus I found the Comfy Cush:
http://www.amazon.com/Comfy-Cush-Back-Pain-Cushion/dp/B00P1TDM28My first impression was this cushion is hard as a piece of plywood. But it soon conforms to your shape under pressure.
After a couple hours it was clear this product solved my problem. I still stop to stretch and exercise but the pain is gone and I can now drive long distances again.
Note: I have no connection with this product and did not receive anything for this review.