Here is an item that has potential for you campers. A
Sanden Scroll compressor that is driven by an electric DC
motor. This would make it possible to use your
airconditioning system without the engine running. Power
requirement details are sprarse except for 320 VDC. This
seems odd but the compressor comes with some kind of power
box. The scroll  is one of the quietest and durable
compressor available. Add a reversing valve and presto, you
have a heat pump! I will try and get more details if anyone
is interested.

http://www.sanden.com/parts/sd7.html

      Ken Lewis
 86 Transporter Crew Cab, 60 T-5 Coupe
 http://neksiwel.20m.com/   O2  sensor monitor gadget, my
cars, Vanagon Tech
 http://EB03.20m.com/  Everybus 2003  pictures