A pal from Seattle and I were discussing the 'movement' to turn Shipping Containers into habitable space. There's just a FEW Containers around the port town of Seattle. Supposedly, there's ~300,000 'spare' Containers around Long Beach CA. It's cheaper to build them new in China for a few hundred bucks than to ship them back.
He pointed out that Containers used to ship perishables are lined with something like 6" of Insulation [Styro?] and then chilled during transit.
If a person could find a used Truck Box insulated to move Food or other perishables - I suspect the separate A/C unit above the Cab would have been removed already - you'd have a comfy Truck Box ready to trick out.
I've walked through a few U-Haul and other Boxes to check out space and live-in possibilities. It seems promising... The front space under the Cabover extension would be a good spot for Utilities or storage. Boxes put on Izusu Diesel chassis are a nice size.
Several Boxes I walked had translucent Roofs, as do the 'PODS' portable Boxes.
http://www.google.com/images?q=shipping+container+homes&um=1&ie=UTF-8&source=univ&ei=fL1aTP7_C4-4sQOy8qFL&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CEEQsAQwAw&biw=1126&bih=737