How do you cool your van (or other vehicle) when you're sleeping in it?

Not sure if this counts as climbing gear...

I built a sleeper platform for my SUV. Sleeping in there on a 30 degree night is great but on a 70 degree night it gets unbearably hot, even though I keep the windows down and I keep a battery powered fan running.

I'm curious how people who have vans, truck bed campers, etc avoid overheating. 

Roof fan. Full blast constantly. Wet towels. Just suffer.

when my camper van broke down, I couldn't run the a'c on full blast right before bed. So, for a few weeks, I was sleeping in it when it was still in the 90's around sunset. It sucked- open all the windows if you feel safe doing so, wear nothing, and stay hydrated. the first few nights will be bad sleep but your body will adjust to the heat after some time. Get used to sweating a lot, all the time.

Roof vents with fans. Evaporative cooling towel.

Move to a cooler location?

My truck bed camper has a fan-tastic fan in the roof, that exhausts the hottest air out. You typically open a window on the coolest (shady) side of the truck. On a really hot day I'll open the slider window in the camper behind the rear truck window so it's pulling in air from the shady area under the truck. I have a solar panel (to keep the RV 12V charged) so I can leave it running all day and keep it relatively cool inside. 

At night I open the window right next to my bed (and close all other windows) so it pulls in cool air across me and out the roof.

I have a hatchback type of trunk, so I just open the trunk (along with door windows). In order to "trick" my car into thinking that the trunk is closed (otherwise some dashboard lights don't seem to shut off), I can just keep the trunk lock in closed position with a stick/tape.

Serious van lifers put a lot of effort into insulation. And use those reflective window shades to keep the interior from heating up too much. Other then that—Park in the shade, open windows, and run a fan.

I don’t sleep in my car, unless the night temps go below 60, myself.

Not quite an answer to your question, but I discovered that sleeping on camping cot on hot nights is way cooler than sleeping on mattress/pad - mattress/pad traps a lot of heat, while cot allows body heat escape.

For car/tent camping purposes I use this - https://www.amazon.com/dp/B001LF3G7M/  It is listed as 7.5in high when assembled, it does sound about right. Might be a challenge when used in conjunction with sleeper platform, but maybe this will give you some ideas.

Not Hobo Greg wrote:

I’ve found this to actually backfire in the summer. You’ll never fit enough insulation to prevent the inside from eventually heating up, and then at night you’re stuck with that heat for longer than if you had used less or none.

Interesting! Will keep it in mind, if I ever decide to live in a van. Though my experience comes from a friend’s van, they really needed the insulation for winter ice-climbing vanlyfe, but I’ve spent many-a-summer evenings hanging out in their van, and it wasn’t bad at all. 

Reflectix in the windows makes a really big difference for me, roof fan full blast sucking hot air out, regular fan blowing air over you while you're in the van seems to work for me!  Or at least makes it tolerable.  

When it is really hot outside, there's not a whole lot you can do.  Find a some shade, or just go into a cafe/restaurant/whatever.  

My van came w a swamp cooler.  Super cheap build, super effective.  

(A bucket lined w swampcooler insulation, holes drilled in walls except bottom few inches, some thin tubing, a tiny water pump. 3" or 4" dryer vent tubing into blower intake. Fill w water n a bag of ice--blows white cold air out of rear vents).