Hmm...any more details you can provide on how effective this is?
In any case I'm working through a way to keep my parked van a bit cooler for my dogs...thus making Mt. bike trips, when they can't join the ride, more feasible. Seems something like this, with the fantastic fan, may be a great setup.
Since it was mentioned, a few thoughts on traveling with dogs.. I travel with two big dogs nearly everywhere I go! Have for over 20 years.
All I can give is some tips and to say use your best judgement.
I have tinted the windows extra dark on all my cars. (6 of them). Some cars simply get too hot no matter what you do so those cars I never leave the pups alone in when its too hot out. In the case of a van build it will be important to heavily insulate the walls and ceiling.
Some cars like the van. Can be made to stay COOLER than it is outside!
Here are some thoughts. (sorry, cut and pasted my own comments from another recent thread on this)
1. Find a shady cool place to park! Preferably one that will be shady the entire time you are gone. Learn to read the sun and shadows a bit!
2. Open as many windows as possible! Airflow is king!! My pickup truck topper area with the slider windows open stays WAY cooler than the cab of the truck ever does! A ceiling fan unit does wonders on a Sprinter/van with windows open or vents. Some units are thermostatically controlled to come on when it gets too hot. I've got a Maxxfan on my Sprinter for this reason. Floor vents help to pull cooler air from under the van and stay stealth.
The Sprinter is large enough that sometimes I just leash the dogs so that they can't reach the outside and leave the doors open when I'm sitting where I can see them.
3. Always leave plenty of water!!
4. Hide the dogs with window tint, sun shades etc. The less they can see the less active they will be and the fewer people will come bother them.
5. Check on them often, park where you can see them most of the time!
6. A roof top vent does wonders. I often raise the top on my Eurovan and you would be amazed at how cool it stays inside since the heat can rise out of the van.
7. Get to know the van and how warm it gets in various conditions. Then you can plan your trips away from it appropriately.
8. Well trained dogs can go with you most places so take the with you as much as possible!
Here is a picture of the pups in the Eurovan. Picture taken from the restaurant we were eating in. This is a busy street. Having well trained pups helps. The Aussie puppy is leashed so that he can just reach the door and the seat but not leave he van.