Epoxy is the way to go. I used epoxy to fix some freeze cracks in hot water home heating radiators 13 years ago and they are still holding up. If you want to weld it, there is a product available (whose name I forget at the moment) that permits you to weld aluminum with a propane torch. It is an incredible product. I butt welded aluminum tubing as a saddle in my canoe with the stuff. It has held my 180 pounds on those joints for over 3 years. The stuff is available on ebay. --I just looked up the name. The stuff I have is called Dura-Fix but I think it is also sold under other brand names. Practical Sailor tested it a number of years ago for welding aluminum on boats and was very impressed