Advice for sleeping bag/blanket on a portage.

I just recently purchased a 60L Hooligan barrel with back pack strap. I'm also looking into getting a 115L seal line water proof bag. It's just me and a friend (2 max) that go, and I'm trying to get everything in those two bags. The sleeping bags I have now are from 15 years ago, so they are quite big when packed. I was thinking a very warm thermal blanket of some kind would be much easier to pack and take up less space, (I don't want to spend 300 bucks on a super small sleeping bag. Does anyone have any good suggestions? Advice on a mat (if needed) that can roll up very tight would be great as well.