A Yeti is all you'll need and a 3-Season one should do you fine.
I did it in 08' with the early model of the Yeti and I forgot the pad I meant to bring with me; bummer. But, it taught me to use that thing between my ears (forget the name). I wound-up just throwing my pack under my legs for insulation and it worked marvelously. Never saw much use for a pad beyond placing between my backside and the rock I wanted to sit upon. I did end-up getting a small pad (about 12"x12") that I used to sit on and as a hitch-hiking sign to hang from my pack. Long live Sharpie Markers!
No need for a pad, but that is only my opinion.