If your hot weather is like mine here in Michigan, when it's hot it is also muggy... an uncomfortable combination.
Spend as much time in the water as possible... setup a sprinkler in your campsite to "play" in for a quick cool down, if permitted.
Wear the minimal amount of clothing that is socially acceptable. Drink lots of water so you can sweat a lot, that'll cool you down.
The stand alone / portable AC use more power than a dedicated unit, for the amount of heat they remove. A dehumidifer will only make things worse, as it discharges its hot dried air into the living space.
You'd need a few KW of solar to run even a tiny a/c unit, and it wouldn't help at night. You'd need a truck bed full of expensive batteries to power an A/C unit all night. I have 880 amp-hours of battery capacity and can run my 13.5k AC for about 2 hours before reaching the magic 50% used-capacity number everyone seems to work off of.
Honestly, if the campsite is that good, put up with the heat - otherwise, look for a site that offers electric.
