I don't have a picture of the friendly side of the UDC handy, but here's one from the back.
It's tricky to see in the picture, but there's nothing underneath it as I've already removed the rotten wood that was under it. The red bit at the bottom is some tape to seal the hole left from the winterizing brass a-b valve that seized up on me and I had to replace it with a different kind.
I'm seriously considering just building a new "UDC" box that would including only the essentials, remove the stupid leaky outdoor shower (which is the source of my rotten floor) and replace it with a pex-to-garden hose spigot so that I can hook up a regular garden hose to the trailer instead. But, before I can begin that project, I have to remove this UDC first.
I really appreciate your help, taskswap!