Update:

1. The original tank had developed a pinhole leak at the rear center corner, due to rubbing and corrosion. The front center corner was badly corroded as well, and would have let go soon enough.

2. There was indeed a drain tube, but the numbskulls at the factory who finished out the bilge blocked it up with a glob of gelcoat.

3. Coastline in Bellingham will make me a new tank no problem, but they can't get to it until the end of August.

4. I can't find a plastic tank of sufficient capacity that fits in the compartment, and I don't know of anyone who makes plastic custom tanks, so that's not an option.

5. I'm waiting on a bid from American Tanks in California. They say they are only a week out.

6. If all else fails, RDS Industries makes a 40-gallon that would fit, and either West Marine or Fore and Aft Marine may have it in stock ready to ship.