I have also tried many different cushions, seats, etc. over the years. Unfortunately, none worked well for any long period of time. In the last few years I've become a minimalist hunter. I don't even take the cushion that was attached to my turkey vest. It's too thin to really help anyway.
I've decided that's it's almost impossible for me to sit motionless for long periods of time. I do try to clear an area before it sit and then, prior to any calling, I kind of wallow around a bit to get as comfortable as possible.
I really take some time to look around the area where I am, after I'm seated. I try to reduce movement as much as possible while I'm doing this. After I'm satisfied, by looking and listening, that no bird is in the immediate area, I'll call...be quiet...call...be quiet. If nothing is happening and I need to move a bit, I just move a bit, slowly and only after really looking around and listening.
All of that assumes that I've not heard a bird and that he's not responding to a call before I sit. If that's the case, I just try to keep my old bones as still as I can and endure the pain.
"If he's out of range, it just means that he has another day and so do you."