I know foamed in fuel tanks quite well....we don't like each other
They are a nightmare to remove and cause death and destruction to aluminum tanks.
Below in the images attached you will find a great way to remove foamed in tanks. Just make sure you cut the foam out from the sides of the tank, the best tool for that is a tree pruming blade.
I would not patch the hole, because, likely your entire tank is shot.
This post edited by GradySailfish 04:53 PM 05/16/2008