Here is a post I wrote on a similar thread on the Wildcamping forum recently.
"I bought two EndlessBreeze 12v fans online from America last year for about £80 each including delivery.(I couldn't find a local supplier but that may have changed since then). I can't recommend them highly enough. We spent several weeks in France and Spain during July and August last summer and the fans were fantastic (no pun intended!).
We would use them in the living areas during the day, even when driving, but the best part for us was at night. They fit perfectly in our open roof lights, so they would blow air over both beds while we slept. It was so hot in Spain last year I don't think we could have stayed away so long without the fans."
If you follow the link below there are some good recommendations:-
Thanks for the replies, this endless breeze has come up in conversation in the past. I remember a chap showing it to me saying that it felt cheap and nasty but the results were astonishing. So I think I might take the plunge. Available on eBay at £99
Yes you are correct, a fan will not change the temperature but does have a cooling effect with wind chill on your skin. I’ve found a fan which you load with ice or water to cool the air which might work?
We used our two Endless Breeze fans in France and Spain last year, in temperatures up to 40+degrees, and although you are correct in that the fans do not change the temperature, they kept us cool through the evaporation effect of a breeze blowing continually across the beds at night. We could not have managed without those fans and I've just packed them again for our next trip which will be from Scotland to Portugal starting this Wednesday.
I think they draw 1.2 to 2.6 amps per hour, so how long they will run depends on the capacity of your leisure battery(ies) and what else is drawing power at the time. We use two Endless Breeze fans running continuously through the night and have only run out of power when we have left something else on by mistake.
Not sure if the requirement is just when driving or extra cooling when camped up?
If when stopped, something that might be worth considering is a way to stop the heat getting into the vehicle so much? Not had a lot of use for it so far but I have some 'Shade Cloth' that I clip to the guttering at the top and either let it hang down and clip at the bottom, or move out a little to provide more distance for better effect.
This is the stuff I bought - https://amzn.to/2ZJZQQK - size wise the 6.6ft x 13.1ft happens to be the perfect size for my LWB LT (Sprinter) both length and width.
This video has some ideas on keeping cool in the heat and also explains the shade cloth deployment better
Space blankets have a gold side and a shiny aluminised side, if you hang one over the windows on the sunny side with the gold side innermost you can have the windows open and let some breeze in. The reflective power of the silver side of the space blanket is quite remarkeable and if you feel the side of the van which is covered you will feel a marked difference in temperature. I.e much lower than the exposed areas.
Says cooler and humidifier. I would have thought that humidification was the last thing you need. The French are warning that their predicted 40C will feel like 47C because of the high humidity. Aircon cools and dehumidifies and an ordinary fan helps cool you by moving the air around but adding moisture to the air does not sound good.
It is stiflingly hot here in southern France . NE Spain is even worse . We are in our house, not camping car.
My weather station is currently showing” 40 degrees but feels like 64”. How it calculates that I have no clue. Its obviously not 64 but it is very very hot.
Due to drop to low mid 30s next week.
These water tank coolers work by evaporation of the air , they are quite popular in Australia , more so away from the coast , ie where there is usually low humidity . The higher the humidity the less effective they are . You use them with windows open as opposed to refrigerative air con which you use with enclosed space. The ones in Australia are usually mounted on Roof , and rely on moving large volume of air , so dont get your hopes up with these little box ones