Sounds like you have it figured out now, but i was going to suggest ditching the Air mattress. They are about as comfortable as sleeping on the bare truck bed.
I have had success in camping trips past with putting a futon mattress in the bed. The texture is right, and it is small enough to fit inside with the tailgate closed (for those of us that can't afford a tent, and opt instead for a tarp.
As for keeping warm...See 54's post...I think you'll figure it out.

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Improvements:
K&N Drop in, Magnaflow muffler, Step Tubes, Reese Hitch, Husky Liners, Nitto Terra Grapplers 285/70/17
Air Box mod,
Improved Fog Light Mod,
dba 4000 series rotors, Akebono ProACT pads, Extang RT Tonneau, RadFlo Remote Res Rears, OEM Hood Deflector
Wish List: Air Horn, RadFlo 2.0 Coilovers, AEM Brute Force CAI, TruTrac, Bass boat...
Donations graciously accepted.