Update on tank
Well, I talked with the manufacturer (Florida Tank Company) and agreed to a replacement price. They sent me the original drawing which I verified this past weekend to be correct. It will take a 3"x18" cut as Sailingcal21 discussed earlier. Given the tank is shot, I have elected to remove the front board pull the tank forward (after cleaning) and cut into two parts to remove.
I am ordering a replacement 3" shorter which reduces the tank volume from slightly over 30gal to 26 gal which I can live with. consequently, I will not have to cut any fiberglass.
As a side note, I have found that Rule makes a 1 1/2" diameter submersible pump that drops neatly throught the full guage hole to remove the diesel and also remove the cleaning solution to clean out the tank. The pump comes with 12 Volt connections plus has a rechargeable battery. This is going to be the ticket for cleaning the bilge and other things in the future. Bought it at West Marine.