uSE A leaf blower.Since the trunk seal doesn't go all the way to the edges of the trunk lid the water could be coming from under the trunk lid on the outside of the seal and running down by the tail lights. Try opening the trunk while drying the car and see if water is under there. If there is, when you start driving it will run back and out by the tail lights and down the rear bumper. Just a thought.
I have a 60 gallon air compressor and a long hose. I use it to dry the front of the car and help dry the wheels. Guess I will try using compressed air to dry the the taillights. I was already thinking about it but never tried it. I don't think it will get all of it because the water is trapped on the inside of the taillights. It might however.uSE A leaf blower.