If the places you sit allow you to sit about 16" off the ground.....you can always do what I did.
Granted, carrying weight is about 5 lbs, but it does come with a carry strap. Hahaha
With weight & health issues making it impossible for me to easily get down on the ground, let alone get back up (picture beached whale)...I had to stop using the stadium seats that I had always used.
So a couple years ago, I went to Harbor Freight & bought one of these:
http://www.harborfreight.com/step-stool-working-platform-66911.html
Made of aluminum, and can hold 350lb man.
The legs fold in for carrying...yet lock in place with latches, for use.
Then, I set to work with camo spray paint, and viola:
Got a couple of 1-1/2" thick camo foam pads, that are sold to guys who want to sit on the ground.
When stand spot was reached, I placed both pads on the platform, and it makes a reasonably comfy seat...as long as your stand doesn't last 45 min or so.
Or your legs don't fall asleep from sitting too long (as mine are prone to do...even sitting at home in the recliner).
I suppose it isn't the best for majorly uneven ground. But, it sure is steady!