Sportsmobile offers a roof mounted A/C on their web site

http://www.sportsmobile.com/options/options.htm

here's the hype from the site:

STARCOOL AIR CONDITIONING A most popular option.
A unique, patented air conditioning system available exclusively to
Sportsmobile. The Starcool is specifically engineered for use in van
motorhomes. It is not a room type or roof A/C that is built in or recessed
in the rear of a fixed top, which cools only when you are parked (110V).

Cools when "Driving or Parked" The Starcool is the only RV A/C available
that will cool when driving (12V) or parked (110V). The van's dash A/C cools
the cab but not much more. With the Starcool, you can enjoy lots of cool air
throughout your Sportsmobile, from a single system. When parked, a 110V
hookup or generator is required. For periods of time, when you are parked,
you can let your engine idle to run the Starcool . You cannot do this with
other RV air conditioners.

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