Thanks Denny. My fuel fill is port about two feet forward from transom and vent just below. Not sure I understand the keelson part. This has a beautifully gel-coated box, more like a coffin, that is part of the entire floor liner, or deck, as did my brothers 1988 18. It will be cleaned, compounded and waxed while new cell is being built. Roughly $9/gallon last time I had one built. Want to get max in there so hoping for about 70 again.
She should not leak again for 20 years so thinking about adhering a few Starboard strips length wise, should water make it in. There is a half inch sized drain in starboard right corner, which was slowly draining gallons of fuel into my bilge.
On my 15 Whaler I have an 18 gal. above deck aluminum cell under rear thwart. This one was primed heavily, then painted Krylon Kitchen Appliance Almond which matches interior perfectly.

No clue of cost of coal tar epoxy. Thanks Again, Michael.
Please check out other post in General "Where's Otto?"