---- Jim Felder <jim.felder@GMAIL.COM> wrote:
The best way to keep the rig cool is to keep it shady. If
> you don't, even if the night is cool the camper will be hot, and so will
> your food and water.
>
> I have not wanted the extra weight or complexity of a conventional awning
> setup, so a year ago I bought a $20 items at Dicks Sporting goods that was
> meant to clip onto the roof rails on a minivan or similar.

(description of Jim's installation cut for brevity)

Jim, I have something similar.  I use a tarp.  To fit the rain gutter, I use a piece of pvc electrical conduit and c-clamps.  The end of the awning is supported by two extendable tent poles.  The whole things stores in a small sack.  Works great.  However, I have not found that it necessarily shades the camper itself, since it does not cover the roof.  For that, I need a tree.

Last weekend I was at a spring-fed creek in the Oklahoma Ozarks, on private property.  I spent much of the day in the water, wade fishing, swimming, or snorkling.  That kept me cool in the 97 F heat.  Took a nap in the afternoon, in the van, with a nice breeze coming off the water through the van.  Night was similar.  But had I not had a shade tree, the camper would have heated up, even with the tarp.  You're right, shade is the most important contributor to coolness in camp.

David McNeely