Took the spoiler off this morning, ice/water mixture was sloshing around inside the whole time. Got it off, two through-bolts through the trunk lid, no problem. It appears that the seal between the trunk lid and two small holes that let air in/out as it expands/contracts (I presume) wasn't water tight.
Two nubs on the spoiler fit into the rectangular white plastic area here. Water seems to have been pooling in the rectangular basins and probably due to capillarity (water's ability to move against gravity and "wick"), water was slowly getting into the spoiler.
You can see the foam seal is moist in several spots. I cut part of it away to expose a larger hole that leads into the cavity within the spoiler.
So the plan? Hmm...Tried tilting spoiler to let water slide to one end, no dice, the water goes beyond the small holes that exist and simply sits in the end. Shake it around a lot? This works, but it'll take a while and you get a few drops at a time at most.
So... Some cotton shoe lace should work as a wick to use the water's capillarity (big word again) to get it outta the cavity. Cut a cotton shoe lace in half and pushed it into the cavity until only about 5 or 6 inches was left out.
Next I shook it around a bit to get the shoelaces down into the water, and water started dripping out almost immediately. I'm letting it sit in my warm basement until I am convinced it is dry. At some point I will go down and ring the shoelaces out and put them back in.
Note that I did this on both ends of the spoiler. Hope this is helpful to someone.