Upload & Sell: On
...Will a better lens handle hot and humidity like any L lens or a better body like 5D with a better sealing?
If the condensation is on the sensor, or inside the lens, then a better-sealed piece might help...or it might not. As others mentioned, taking a cold camera into a moist environment is problematic. Keeping the camera in the boot instead of in the passenger compartment can help.
(Don't keep it in the boot when the car is parked in the sun for long periods, as it can get too hot.)
I used to live in Florida, but moved to the Pacific Northwest many years ago. The last time I visited Florida during the summer I couldn't even sleep without the A/C in my hotel room going full blast. On my first morning there, I stepped out of my room and my (cold) glasses instantly fogged over, and I had to take them off until they warmed up a bit. I could see better without them than with them when they were foggy. The next morning I ran them under hot water for a few moments just before I went outside, and no more problems.
I don't suggest running your camera under hot water, but the principle is the same: if the camera and lens are as warm as or warmer than the surrounding air you won't get condensation.