I know that a few campers love these type bags, but for the life of me, I fail to see much advantage over a regular set of bedding. I need to be enlightened.
I see a couple drawbacks, like how does one kick the covers off your feet if you get too hot during the night? Also, they must be bulky, to have a full set of bedding above and below you, no.
We just use a mattress cover and sheet, then top with a thin down duvet. We keep the sheet tucked in at the bottom of the bed, but the duvet loose on top. In colder weather (near or below freezing) we bring along a wool blanket to add to the mix. Even with this setup, the duvet is piled up between us, with just a sheet for comfort.