The week before Alumafandango here in Denver we were checking the weather and it was supposed to be in the 90s every day. With no hookups, parked in a dirt lot for a week, and having to work a good chunk of each day inside the Airstream, we guessed it would probably be less than comfortable. We've boondocked when it's really hot, but there's always been water nearby for swimming or sailing or whatever. This week is all about work, and socializing and seminars, and no A/C.
We were talking about swamp coolers and I decided just for fun to see if they made small portable swamp coolers. Well, check this out! I found this tiny little tabletop one called HandyCooler! It's got a sponge insert that you keep wet and it blows a remarkable amount of cool air out. It runs on batteries or USB and you can get a wall adapter separately for it if you need that. So far, we only use them when we're sitting at the dinette working and they power just fine using the laptop's USB. They sit nicely and compactly on the table and we love them.
They're $29.99 at Amazon and we got two of 'em. You can go ahead and laugh, but it's totally worth it. (They also come in pink and blue, if that's how you roll.)