if your going to hunt from the ground you just have to get used to it. I hunt on the ground nine time out of ten so I know what your talking about. The three legged stools tend to sink in the ground and are not real stable. If you really need something get a small camping chair, comfortable, stable and still easy to carry.

I have a small ground seat I got from cabelas. Its made from closed cell foam. It was a bit pricy but the price is worth the comfort. fold up relativly flat to hang from pack. the back is attached to the seat with adjustable straps depending on if you sit on an incline or such. Before that I used a hot seat available all over they only cost 5-10 and are effective but not nearly as comfortable. But I still keep one in the truck for my buddies to use!

foam cushions work well, but I use a blanket or a sweatshirt. If you dont hav to, dont buy anything extra: thats the way i go

a few places sell a small three legged stool that folds up and is pretty compact might be worth checking into ive never used one myself

Lots of leaves or a pad seat to bring with.

a stool or chair for sure will help or a hot seat

If you are not going far can make a T seat from 2x4 lumber. Just lean it against the tree and take a seat. They also make seats that strap around trees. Very comfy but some are quite loud.

Check out the very cool product at www.beavertailstalkpad.com which will solve this problem like you won't believe!