In 1956-1959, Ohio Marketing experimented with offering a "Custom" version of its trailers, called the "Custom Fleet" for a 10% up charge, and attempted to limit changes on its standard models, the "Cruising Fleet" to control costs. Airstream assigned a unique serial number to 10 of them, but mostly just appending a "C' after the serial number of the standard serial #.
It was all rather silly, as up until then, you could get any Airstream customized to your layout and option desires anyway. The concept seems to only have lasted a few years until 1959, with Airstream going back to offering custom versions of it base models.
California was unable to offer such layout customization as they had to follow the strict California Division of Housing regulations and approvals.
Here is one of those unique serial numbered 10, O- 8009C. It is based upon the 22' Flying Cloud, but does have a very unique layout with its symmetry from front to back, dark wood cabinets, and the lack of Princess range - just a 2 burner stove. The last set of the images is the trailer interior s found before restoration by the owner.
What is puzzling, is that production records indicate this trailer was made in mid 1956, yet it has the 7 panel end caps of a late 1957 trailer. Either the Airstream records are wrong, or this was one of the very first 7 panel trailers, and maybe why the unique O- 8NNN s/n.