I have the exact pad ribka mentions above. It is very comfortable, an R value of 3.7, weighs 1#11oz in rectangular large.
Took it to the ANWR last year on a DIY 10-day caribou hunt and couldn’t have been more pleased. I coupled it with a Western Mountaineering Sequoia bag and it worked great.
I would seriously recommend a larger size than you might think, as the extra width was very nice (I am 5’9”, 195#, and I was glad to have the larger size).
