I guess I am late on this one but I would have suggested JB Weld, Scuff up the metal and apply epoxy then sand to smooth finish.

Glad to here it worked out for you.

 

Seriously on the welding bit. lol I have done it on my 7 after pulling a dent out of the tank.

 

I believe your right, proper flushing and removing the fumes before the flame and your good. My buddy had to weld a crack in his 200 gallon aluminum fuel tank on his boat. Drained it and flushed it with something made to remove the fuel and it welded no problem.