[Duflar]

One thing you could try after that is dried, Put the sprinkler on your car and sit in the rear seat. Keep checking the floor, if you begin to see/feel water look around for where it is comming in. If you don't see where it is most likely comming in from under the carpet. Perhaps from the trunk area and flowing along the metal floor under the rear seat and puddeling at the rear passanger floor. Strange it's onlt the passanger rear right? Maybe a clue, whats different between the right and left rear of the camaro vert?