Vent covers and leaving the vents open will help a lot.
Since you're storing it on your property next to the garage, window awnings would help. Plus, you could then leave the windows open while you're at the house.
Use the insulated foil to cover the inside of your windshield. However, the heat first hits the outside so a good window covering on the outside windshield would help greatly.
If you have a pine pollen problem I wouldn't leave the fans running and pulling in dirt and pollen.
Perhaps the smell you have is the beginning of a mold problem. Check your ceiling and walls for any water damage issues. Keep your mattress pulled away from the wall a foot of so so air can reach that wall. Keep your cabinet doors open to let air circulate. You also might consider running a dehumidifier since you're there to keep a watch on it or let it drain into a sink and keep your gray valve open.
Since you're in Florida you have more moisture issues than those of us our in the Western states.
Good luck.