For car camping, we put a fleece blanket on top of our air mattress *before* bedding. Wow does that make a huge difference! Fleece is an amazing insulator.

I have a question that is a culmination of a long chain of thoughts. Let's see if I can encapsulate the thoughts — and please correct any wrong step! Sorry if this is too-big a question. I've been sitting on these thoughts until I'm about to explode! :)