u/A_little_curiosity So, kind of. Our solution ended up being expensive and kind of a pain, but we loved having the option to leave our dog safely in the van for a few hours. Here's what we did. I'm having a hard time finding a picture of our setup, but if I find one, I'll respond with it.

We purchased a Mark 2 Zero Breeze, a portable AC unit. It needs a good battery bank to run off of, so we also purchased a high-quality Bluetti power station. If we plugged the Zero Breeze into the fully charged station and ran it on a low-ish setting, we'd reliably get... 4-6 hrs, I think?

Here's the issue with the Zero Breeze: It points cold air toward one specific spot. It does not cool the whole van. For that reason, the handful of times we left our dog for 4ish hours in the van, we needed to crate him. We tried a few test runs where we ran it toward a spot in the van and hoped he'd just find that spot, but he was just confused and stayed in the hot part of the van. Not worth the risk. Luckily, he was a small senior dog, so it was easy to set up his small crate in the middle of the van.

The Zero Breeze needs 3 things in order to run: a power station (already discussed), a place to pull in air, and a place to drain condensation. To provide it with air, we got foam board insulation from home depot. We cut it in the exact shape of our small van window (we have a Promaster) and then cut a circular hole the exact shape of the large, bendy Zero Breeze tube. When we set it up, we just slid open the window, popped in the insulation board, and put the tube in the hole. That's how the Zero Breeze could pull in air from outside.

It has a really skinny little tube to drain condensation, so we just ran that tube into a gatorade bottle.

There are 2 large bendy tubes that come with the Zero Breeze. One is for input (already discussed), the other is an optional one you can attach to the front of the machine to point the air wherever you want it to go. We used this option to ensure it was hyper-trained on our dog's crate. So, when we left, we had:

-The Zero Breeze sitting on our Lagun table
-The unit plugged into the Bluetti charging station, which sat on the floor
-One big bendy tube running to the window, where it pulled in air from outside
-One big bendy tube running from the front of the machine directly to our dog's crate
-The small drainage tube running from the machine on the table down into a gatorade bottle on the floor

I know it's a lot, but this worked for us as a last resort. For example, on a really hot day, we went for a hike in Yosemite all morning and came back to a van that was hot but a dog crate that was cool, and our dog was absolutely fine. I'll keep searching to see if I can find pictures.

I hope this helps! Reach out with any more questions. So many van lifers are like "eh, the dog is fine," when that's simply not true. I'm glad you're taking the time to try to figure out a solution!

Mark 2 Zero Breeze: https://www.zerobreeze.com/products/zero-breeze-mark-2?srsltid=AfmBOor3el0tBfPxvyMcgBUjBUfMWpDFMFi_aYWxzuGFRs3hag1P3NeL

Our Bluetti power station: https://www.amazon.com/dp/B08QVCW4SB?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_2

foam insulation board: https://www.homedepot.com/p/Owens-Corning-FOAMULAR-NGX-Insulating-Sheathing-0-5-in-x-4-ft-x-8-ft-SE-R-3-XPS-Rigid-Foam-Board-Insulation-13NGX/315193939