Al -
I'm sorry you didn't spot
http://www.trailmanorowners.com/foru...ead.php?t=7720. To summarize, when my gray water tank developed a leak, the dealer couldn't replace it - it had to be done by the factory. The tub and the tank were solvent-welded together at the fittings, and they had to saw out the tank, break the fittings joining them, then pull the tub up off the floor. I think they also had to cut out a hunk of the floor under the tub, and then replace it - judging by the fact that the floor beside the tub has squeaked since the job was done. Can't be sure about that, though.
I agree with your conclusion - don't replace the tank if you can find any way to patch it!
Bill