Going backwards today. Removed the right tank cover plate and sender and got a look at the inside of the tank; primarily the backing plate area behind the T905 angle support that is on the outside. The proseal has the appearance of having a second coat of proseal applied. This indicates that the factory may have had some problems with this leak. Just a guess.
Van's forum provided some good advice and suggestions. I just do not want to move too fast here. I am not sure if I should proseal over the tomp of this mess, or try to peel some of it out of there first.