If you're confined to camp for any length of time, which is pretty much guaranteed on a big mountain, you're either sitting down or standing around. For the sitting portion of the event we recommend you take a load off in the Big Agnes Cyclone chair.
There are a lot of chair kits out there of the "just add pad" variety. What sets the Cyclone apart is that it weighs just 6oz. It's basically a very thin piece of Cordura with some aluminum stays and a couple of nylon straps for adjustment. It'll fit a 20" wide pad up to 78" long, doubled over at the southern point of contact. The Cyclone feels just a tad less supportive than some of the beefier kits, but it's still plenty comfortable when stuffed with a 2.5" thick inflatable pad. It'll work well with a mummy design but not so much with closed cell pads, which don't provide enough stiffness.
The instructions say "requires extra care" due to the vapor-thin construction and that's certainly a caveat for those who tend to be a little rough on their gear. If you use it on a hard surface be careful of not only abrasion but loading it too quickly, which will stress the stays and possibly cause them to erupt like little metal aliens from the fabric. Not for everyone or every situation, but if you're looking to cut every extra ounce and can put your ass gently into that good seat, sir, then you're good to go. For those who instill fear with their rear, consider a heavier but sturdier model like the Therm-a-Rest Trekker.