Years ago I knew a bloke who built a house out of a truckload of composite refrigeration panels he bought from some second-hand yard. The house was just south of Sydney and it was freezing cold in winter, but the house was toasty as inside. The design was just a matter of getting the roof and ceiling up and then connecting the composite panels to make the walls. Simple and practical.
I see that Jayco campers make good use of composites, among other builders.