soaked
My trunk also gets wet! And it gets all mildew smellin' and stank in there!
The florida downpours have been also filling my passenger side taillight full of water!!!! It got full of mildew in it too. I had to take it off, drain it out and fill it full of bleach and water to kill off the nast crap! It was a mess! Since then the inside of my trunk hasn't been getting wet. SO I suspect my light housing was the cause. This could be your problem too I'd imagine.