We have a 2006 Coachman Spirt of America tagalong and we noticed that the floor under the bed and storage area was spongy. We tore it apart and it the floor was saturated and moldy. We have left it open to the studs and have noticed that it seems to be wet right near the back storage door. We have caulked this area and all the seams along this area but after a recent rain, it is still wet. We haven't replaced the floor yet until we can find the leak. Any ideas?