Bob,
If you were in West Texas,New Mexico or Arizona, the mist system is the way to go - it provides moisture (humidity) which cools the hot & dry air. BUT...in South Florida (like here in NOLA), when the summer temperature goes up, the humidity also goes up - and a mist system will just make you wetter and more miserable!! You need a dehumidifier / air conditioner for the inside of the rig - and venture outside only when necessary to do so. (That is why you see streams of water (condensation) dripping from those window units.) I think you need to rethink your plan for happiness in a Florida Summer!!!