I have been having a hard time deciding what to put on the bottom of the trailer for protection. I was debating between epoxy and the dreaded black goo. In the end my frugal side won out and black goo it is. I used Henry's 107. It was not bad at all. It dried fairly fast and I did not get a single drop or smear on me or my clothes.
Here is the floor upside down ready for the black goo. The front drop floor section will be located under the front bunk bed. It will be used to store a spare tire and other items that I will not need very often. The second drop floor section will be where I stand inside of the trailer.

This is after the black goo was applied. I used a brush around and between the dropped floor sections. I used a smooth roller for the remaining flat sections. I used painters tape around the outside. These areas are where the walls slide on and also where fiberglass will wrap around.

Dan