Hi! From Louisiana here - so pretty experienced with hot & humid summers... our approach is similar to info above:
We always pack 2-3 pairs of great walking shoes per person. We swap out socks & shoes during midday break daily - it’s a little foot refresh.
Sarnal lotion - great for the golfers rash that I usually get on my ankles by day 3 or 4.
Cooling towels - we get a cup of ice water - drink the water, dump the ice in the ziploc with our cooling towels.
Gatorade mix ins - we carry chilled water bottles into the park & ritate plain water with Gatorade waters.
Sunscreen - face, neck, lips. Hats too.
Athletic shorts & Body Glide. ‘Nuff said
Moleskin - if you get even on lil rub your have a painful blister, moleskin is the best thing other than prevention.
We carry throwaway $1 ponchos but also have reusable ones at the hotel in case a full on rain day is predicted.
*ive never worn dresses at Disney, but the thread comments above are making me curious so I plan to buy & try.