Adding wire reinforces the joint. If you need a soldering iron, here is a great kit: http://amzn.to/2hKViHw If you have a little more money this is my favorite: http://amzn.to/2h29xYB
Some tips on the proper way to install a aluminum fuel tank in boat. Which does not include foam or fiberglass. Only Neoprene rubber, 5200 , screws, and thats it. Dont use anything that holds water like WOOD or FOAM it will cause crevice corrosion.