hi there,
i am checking out putting a roof top aircon into my 1975 v4 essex camper.
here is a good site in the uk.
it seems the unit is only 340 pounds or around 600 dollars, so this would be a good way to cool your van.
here is the link.
http://www.outdoorgb.com/p/12v_air_conditioners/maybe you could also run a vent system so you can pump some air into your cabin while you are on the move?
thats what i am looking at doing.
regards,
geoff.