I have debated for years weather I really needed air conditioning with the van parked and kept telling myself that a roof vent fan, other fans, and a window vent screen was enough, and I didn't want to fork over the $1000+ to do air conditioning. I finally caved in but came up with a way to do it for under $200 and very easily.
There were a few options I considered, but both involved a lot more money and I really don't use the AC that often unless I am near a plug in.
Zero Breeze Battery Powered AC - The idea of this is great, but I am not confident that this could keep up with summers in a black van. I think if it was just two people sleeping with no pets this may work, but my 12,000 btu is much better at keeping the dog cool when we are out and about. They advertise that this does 2300 BTU, which may work for small vans to cool it down slightly. But my van is black, and it gets really hot. I do like that this is a two-hose system, much more efficient than mine, but will require two vents in the van to work.
12v DC Truck Style Mini-Split AC - This may be the way I go in the future, but it is still a very high demand for my current battery setup. This may work for people with a larger battery bank, but I have only 300ah or so with lead acid batteries. This one would take a bit of work to install also.
I may look at these options down the road, but for now my $200 investment is working great.
Step 1 - Purchased a used portable AC unit. I purchased an older used version of this unit on Facebook marketplace for about $100. This one has heat, air conditioning, fan, and dehumidifier mode. I would suggest getting at least one with heat and preferably with two hoses (mine only had one, I'll get into that later).
Step 2 - I bungee corded it to the back of the front passenger seat. For a while I would move it to the middle of the seats when parked and then run the exhaust hose out the window of the van, but that took a lot of setup time so I changed that. I cut a large hole in my floor for the exhaust hose and condensation drain hose to go through and added a bug screen to it and aimed it to the rear of the van underneath. I also spray painted the PVC vent black so it didn't stand out.
Step 3 - Hook up the 120vAC line which is provided from an outlet in my van that is made hot only when the van is plugged in to shore power or a generator (the only things plugged into my 120vAC outlet are a battery charger for the house battery and this AC unit). For my generator I have a Craftsman 2200i inverter/generator and it will power this unit.
UPDATE (2024): This system is still working great. I have run it on my portable generator in a pinch (generator is housed in our trailer) and it does run. I use the heat pump function on this much more than I thought. If you go this route, I highly recommend getting one with a heat pump. Great way to heat the van without burning diesel or propane when plugged in.