In Florida humidity definitely requires some effort to control. My PC is in use about 50% of days October thru April, but a bit less in summer. When not in use, I keep the AC set at 85 in summer and the heat set at 55 in winter, plus a dehumidifier set at 45 or 50% (and the bathroom door open, since there is no direct route for AC or heat into there).
I too am concerned about the excessive hot/cold in the cabinets over the driver and passenger seats. I'm planning to do something to improve the insulation in there, but haven't quite figured out yet what I want to do. The other temperature/condensation problem points I want to solve are the metal window frames and the plastic vent covers, which are allowing way too much hot/cold temperature exchange. I have the double pane insulating windows, and the glass is doing its job, but the metal frames are extremely conductive and no thermal break at all. The vent covers are too shallow to put the thick pillow insulators in, so I have the thin silver bubble type, but they don't create the air seal that I need.
Then there's the cab. I already insulate my cab windshield and windows, but I also want to be able to completely block the entire cab area in cold weather camping, as the cab really pumps cold air onto the floor.
Lots of projects.
