Hey guys I'm new to this stuff and have been using my sleeping pad in my DIY hammock works alright but I get tiered of it slipping around in the hammock so I want to try a underquild. My questin is about the underquilts raising. Sy I got a 20degree underquilt but I have a 0degree sleeping bag. Would the temp raising still be at 20 degrees? Or do both the sleeping bag and the underquilt need to be say 0 degree to keep me warm at that temp?