I guess this is just a FYI. Maybe it will help others or maybe not but it seemed worth mentioning.
The rear bulkhead on my coach (1989 U 300) showed no signs of separation. Over time I've noticed the battery tray "sinking" into the floor. The underside didn't show any signs of anything to be concerned about. It finally started to show some signs that something was wrong about a month ago. I removed the battery tray and found that the tray was no longer attached to solid metal. I started cutting out rusted 1 1/2" tubing and the upper and lower fiber glass skin and the insulation. Long story short i cut out the whole basement floor from the rear bulkhead (which was solid for about 3 inches forward) to almost half way up the coach to solid not rusted metal to start a repair from.. 80 ft of 1 1/2" tube, new insulation and skin material later I now feel that I won't hit bump and have two coaches.. Big job..
My point is just because there are no signs of bulkhead separation doesn't necessarily mean that all is well.. If you notice any changes in the flatness of you basement floor don't ignore it like I did..
Please tell us more... did you do the work yourself? How about the attachment to the vertical compartment walls? Did you reuse the old Rolok bolts or through bolt with nuts? Take pictures? What did you use for the bottom skin? The Filon fiberglass material is not that easy to come by in my experience... any details you could share might help somebody else out of a tough predicament. Just saying...
Don
Andy,
Were you able to identify the source of water entering the basement floor sandwich? The wet bay/poor housekeeping is the "usual suspect".