Water from the bathroom or water from outside?
Assuming outside, I would make a careful inspection of the roof in the front half of the TT. Look for cuts and separations. Pay special attention to sealing around trim, edges, and around any fixtures on the roof. Next check the window nearby for sealing around the outside where it joins the siding.
It is less likely, but water can migrate from the source and show up in odd places, so I would not rule out the bathroom. Condensation from use in cold weather, and leaking containers in utility storage under the bed are also possibilities.
The fiberglass panel on the outside may have seams. Sometimes they crack and admit water. Carefully inspect the wall outside.
I wish you good luck and happy trails ahead!