THen, ya gotta figure out how the water got in there, from what I understand the most common reasons are:

SRTS - leaks around the wing's mounts.
Base/Limiteds - leaking hoses for the drains under the spoiler - they discharge above the license plate area on a Roadster, not sure on a Coupe.

ALSO, I think some have had leaks somehow around the gas cap filler area.