That's a pretty basic design for a swamp cooler, but you can go even a bit more low-tech by simply taping a damp bath towel to the back of your box fan and placing the bottom of it in a container of water - preferably one large enough so you don't have to scrunch the towel, but just use the largest container you have. And while ice water is optimal, pretty much any temperature of water will be better than nothing.

I should have added: a shallow container. Something like this is ideal:

https://www.target.com/p/sterilite-32qt-clear-view-storage-bin-with-latch-purple/-/A-13794492

So many people - old, poor, disabled, homeless, etc. - will not be able to escape the heat.

And let's not forget that no Amazon warehouse has air conditioning (they keep ambulances on call instead, because you know, god forbid Bezos spend any money on air conditioning in the warehouses).

If possible fill your bathtub with cold water. Add ice from freezer as needed. This saved me so many times when I lived in NYC and had to reduce my body temperature.

Window air conditioners are a Godsend at times like this. And they're cheap.

“House”? “Upstairs”? “Downstairs?” lol. Must be nice to have that kind of money.

Regarding dehumidifiers, humidity generally isn't an issue in the Sound, and keep in mind that dehumidifiers give off a fair bit of HEAT. They basically work the same way an AC unit does; a set of coils gets cool (this is where the humidity condenses into water & is removed from the air) and another set gets HOT. But unlike an AC unit, the coils which get HOT are not pointed outside, so the HEAT is pumped into the room. Due to typical inefficiency, the added heat exceeds the added cool, so a net warming effect. A room/window AC unit will do the same dehumidification, while producing cool air, but will pump the HOT air outside. With any luck, that HOT air will be sucked up by the window fan of that PITA neighbor you can't stand...

I got central a/c installed in my house in May. Suck it losers.

Bowl of ice. Think about where that ice comes from. Typically a freezer sitting in your kitchen. Which means the refrigeration system has to work that much harder and pump more heat into your dwelling.

On the other hand, if your major appliances are sitting outside on the front porch like some of the finer people in this town, go for it.

We go to sleep with a wet wash cloth or hand towel draped across out torsos and a fan aimed at the bed. Learned that trick living in an un air conditioned studio apartment in Chicago. We also would lock ourselves in the bathroom with a cold shower running back then. That cooled off the bathroom quite well, and then we would draw a cold bath, drag the TV to the door of the bathroom and eat dinner in the tub. The cat spent every summer I lived there parked behind the toilet against the cool porcelain.
Right now we have blocked off most of the house and are camping/sleeping in the living room where my poor little mobile AC unit with the aid of a ceiling fan, oscillating fan and two tiny personal fans from when my father in law was in the hospital, is valiantly trying to keep the room under 90 degrees.