Boxerdog,
Don't forget what KC said about using a sleeping pad on a cot. Or a wool blanket doubled over if you don't have a pad. But a closed cell foam pad is pretty cheap.
A cheap foam pad is a necessary accessory for sleeping in a bag on the ground or on a cot. Remember that a cot has no insulation unless you add some with a pad of some kind.
I recently had a discussion with and old hand. We both started camping and backpacking in warm climates a long time ago. He slept on the ground with only a tarp and claimed that I was a whimp because I used a cheap foam (Ensolite) pad. I said that I liked my luxury. We both had a chuckle over that.
