Underbelly wet!!!!

I have a 2015 178. I discovered I had a wet underbelly when installing back up lights at rear of trailer. Probably the last 6-8 inches of the bottom of the floor. First thing I did was move the trailer inside and start a drying process, I didn't remove anything. Secondly I sealed the spoiler with eternabond tape. I kept the trailer out of the weather all the winter months. I moved it outside, and monitored the floor are for wet, near all the water sources, it stayed dry. One thing I noticed was the protective black undercoating holds water in, there is no way for water to drain from the floor. The floor is dry, so it appears the spoiler was culprit in my case. I could test it with an awl and find wet areas. Once I penatrated the black covering, if it was wet I'd get a drop of water. For me it was a matter of getting it dry and then trying to figure out what would make it wet. I wasn't ready to just quit and get rid of the camper until I tried to fix it.