Hey guys, just wanted to give an update. First off, thanks for everything, I wouldn't have found the problem, let alone the solution, without everybody on here. Glad there's a dedicated community to our car. I've uploaded some pictures showing some of our various steps.

My father and I started by taking the interior panel trim off, then the wing plate, and then the spoiler. As you can tell from the attachments, there was a lot of corrosion around a few of the screws and around the spoiler connection. Around the wing plate itself, the gasket was completely ruined and pushed way out of place.

Basically, we replaced the OEM gasket with a EPDM rubber weatherseal. We placed it where we did in the pictures because we wanted a flat-to-flat connection for a better seal... it might result in some water resting just above the Chrysler emblem, on that little shelf, but that water will likely evaporate / trickle out, whereas we felt this would give us better internal protection. We also replaced the O rings on the spoiler and wrapped the spoiler's studs in teflon tape to help seal out water. Lastly, we used some WD-40 spray on the spoiler-to-wing plate connection area to help prevent any further rust. We also, of course, removed the rust from all the parts before reattaching.

We're avoiding taking the styrofoam blocks out, thus far, because we think the water that's already in there can be evaporated out or sucked out through driving and then dried... I'm hoping to avoid it, but we'll remove it if it's necessary. We tried removing the rubber plugs, but there were no signs of water. This fix hasn't been tested yet, but hopefully it's completely waterproof now - we want to remove the water already in the trunk before we perform any waterproofing tests.

What do you guys think?