So I'm in field and stream the other day and see this little curved mesh backrest. I'm not usually one to buy things like that but my back hasn't been liking me much lately so for 12 bucks I thought what could it hurt. Carried it in with me today and all I can say is wow, this thing is great. I'm actually comfortable. My safety harness isn't digging into my back, I can't explain how nice this thing is. Just thought I'd throw this out there.
The best thing I ever did was rehab my seat and back with new foam from a fabric store.
The new one was not only better than the old, I saved the cost of a new one.
The next best thing, maybe the best, is I never left the seat out in the cold over night. I found those carries were worth it.