I've used epoxy to repair chain saw gas tanks before...
but they aren't 4 gallons...
are made of a different plastic most likely...
and they weren't between my legs.
You could try. I might do the same.
Keep in mind the Ducati plastic tanks have been problematic.
You might check with a dealer to see if you're eligible for a free replacement.
http://www.ducatimonsterforum.org/index.php?topic=25074.0http://www.ducatimonsterforum.org/index.php?topic=43639.0