The good news is that my water damage from the washer wasn't as bad as it could have been.  Thanks to the advice I received from my other MRH post I cut a hole into the drywall to help the area dry out.  I also put a small fan outside of the railroad room blowing into the rafter area where the water was located.  Although the water did lift the paint and some of the drywall mud, the drywall itself appears intact.  The repairs should be limited to spackel, paint, and a dummy return air vent (with black cardboard inserted) to cover the cut out section.  The dummy vent would also serve to "vent" any future water leaks.  The area directly under the cutout thankfully doesn't have any layout.  My future railroad expansion will definately have a suspended ceiling.  The picuture below was taken from the floor looking up at about a 70% angle.

Thanks to all who gave their suggestions!