Macojoe brings up an EXCELLENT trick. I am a semi-experienced welder and there has always been this taboo around welding gas tanks for obvious reasons. The vapor is obviously the most dangerous part. However, if you displace all of that vapor with water you have no problem.

Well, you do have 3 possible problems: 1) Aluminum conducts heat really well and also water conducts heat really well. Question is with all that water in there will the weld bead get hot enough.....kind of like trying to solder a pipe with water in it. 2) As soon as you say the word "Gas Tank" welder run away. For this reason, You may need to borrow a welder or do it yourself. For aluminum the easiest way will be with a TIG welder. Not everybody has one (MAYBE a tool rental place) andof course the skill to run it. I've heard you can do aluminum with torch welding if you have the right rod. That would req even more skill. 3) You'll ave a TON of excess water to get out and will probably need a 55gal drum of dry gas!

Summary: I think a weld would be far better than any patch. With water in the tank it simply cannot explode. The first option is to find a welder who is willing to do it. Second opt is to borrow or rent a TIG welder an do yourself. Ask wellcraft what the alloy is and get some slabs of aluminum of the same thickness. Drill a tiny hole and practice in you garage first.......You could pull this off !