The Royal Navy Phots who accompany the Arctic Exploration guys on HMS Endurance and the Royal Marines' Arctic and Mountain-Warfare Cadre in Norway told me how they stop cameras and lenses misting up - never bring them indoors when moving from cold/wet to warm/humid. They keep them outside (or in a room where the temperature and humidity is similar to outside).
To that end, an empty Peli-case lined with a terry-towel or at a pinch, a large plastic cool-box of the sort you take on family pic-nics could be used.
Put the (dried as much as you can) cameras in the cool-box before putting them in the car. That'll keep them at ambient outdoor temperature until you can perform a thorough clean and drying...
If you need to move back and forth from the car and it's pouring-down, keep the cameras inside the box in the boot of the car where the temperature should be nearer to that outside.
Then when you get home, keep them in the closed Peli-case/cool box so the camera's temperature gradually adjusts to indoor teperatures - that way condensation shouldn't form inside the lenses and bodies.