I haven't read all the replies, forgive me when I repeat. DH is a sweater too, and hates Orlando b/c of it. When we travel there, he and boys absolutely swear by wicking clothing. Even their undies are moisture wicking, and you don't have to spend a fortune.
Start with the underwear. They wear longer wicking boxer briefs. I think the Hanes brand are $14 for 3 pair. Then moisture wicking shirts and shorts (loose cargo types seem to work best for them). Hubby swears by his Keen sandals. All of us have the H2 variants which dry quickly and aren't made of leather. If they wear sneakers, they wear the kind that are mostly mesh instead of leather, and they go with a moisture wicking ankle sock (again, Hanes makes good ones that are reasonably priced). Dh also uses Body Glide on his inner thighs to combat moisture induced chafing. We have a big bar at the condo and I keep a smaller one (made by Band-Aid) in my park bag so we can re-apply as needed. Depending on the park, there are misters that dh stands in whenever possible, and we drink, drink, drink. We try to keep 2 full water bottles for the 4 of us at all times (we are fine sharing).
If we go back to the room during the middle of the day, dh gets into the pool or lazy river to cool off. Has a shower and complete change of clothes before we head out again, and he changes his shoes so they have a chance to air out.
We try to get to the parks early to do things that involve being outside. We plan meals and dark rides for the middle of the day when it's hotter.