One solution here, cheap at $93:

http://www.walmart.com/catalog/product.gsp?product_id=2067704&cat=14940&type
=1&dept=4044&path=0%3A4044%3A4064%3A92523%3A14940

Another solution here, and indoor A/C unit that does not require window
mounting.  This unit can simply stand inside the Westy, but it's *choke*
$447:

http://www.walmart.com/catalog/product.gsp?product_id=2025454&cat=14940&type
=1&dept=4044&path=0%3A4044%3A4064%3A92523%3A14940

One fellow designed supports and a panel which mounts a small window a/c
unit in the passenger window of a Westy.  Cool camping and it's easy to
remove.  I can't find the link at the moment.

Chris S.
'85 Westy
www.knology.net/~vw/
http://groups.yahoo.com/group/wolfsburg_campers