Jay Series RK 2650 water beneath the floor

[SpottyDog]

Bought a used Jayco Jay Series RK 2650 Fifth Wheel 1994 from a private owner and I'm looking for a diagram of where the pipes are.
I was only able to find a manual that covered several different models.
When we hooked it up to water and began using the shower and bathroom, water began to seep up under the floor in the hall and moved down into the main area.
Would like to know where the pipes are before we cut into the floor to find them. Seems to be either fresh clean water or grey water from the shower (seen some possible soap suds, didn't smell bad)
What would be the best way to reach the leaky pipe and fix it while tearing out as little of the subfloor as possible
Are there even any pipes in the floor that drain from the shower or does it drain straight down into the tank? Perhaps there are only fresh water lines in the floor? Do any diagrams exist showing where all the lines/pipes are? Any information at all would be appreciated

[Grumpy]

Nothing is "IN" the floor everything is above, below, just going though an opening or in a wall. With a unit the old JAYCO will no longer have the schematics either.