Down in the hold where the vehicles are stored, it's usually on the cool side which will help if you leave food in it. If you do, I'd leave it as full as possible and on the coldest setting for several days before.
Between now and then, I'd experiment with the freezer. Buy a remote thermometer so that you don't have to open the freezer to check the temp. Fill the freezer, maybe with ice if you don't want to use food. Park the TC so the refer is in the shade, and see what happens for 36 hours. Use frozen milk jugs with water and you won't even have any water to clean up. This will give you a good idea of what will happen.
Bill