Best I could tell I had the fresh water tank fill hose blow off when I stuffed a hose in it. Water went down through a hole or 2 and soaked the plywood. There is no way to dry such without pulling the linoleum and the Tyvek underfloor covering if you have such. Of course by the time it's soft, it's shot and needs to be replaced. My soft spot was about a 3' area, ended up replacing the leading 4' of the trailer. About 60 hours work. Much mess, much work, much frustration.
The soft area is does not necessarily coincide with where the problem was. When I removed the flooring I could tell by the stains water had leaked in at the 2 exterior storage doors to the front pass through and the water heater door but the soft spot was in the middle of the floor.