Adding beef to the pan is a great idea, especially if you have the tendancy to wheel in loose rock or trees. I would weld it on before trusting an adhesive to keep it in place, but I am an expereinced MIG welder so that may be a factor as well.
Having welded on oil pans before, the best process is to remove the pan, clean all the paint, dirt, oil, varmint splatter, etc from the outer surface that you want to weld on. BTW, clean the oil from the inner pan surface with brake parts cleaner prior to welding so you don't wind up with a petroleum fire............
Using a MIG welder, attach the heavier metal to the oil pan surface using short welds (.25") and concentrate the heat on the thicker metal, moving your puddle to the thinner pan metal. This will help keep you from burning through the thinner metal. You will also want to avoid heating the pan up too much or it could warp and then proper sealing in the gasket/seal areas would be an issue. Make a short welds and then letting the metal cool to touch will eliminate this problem.
If you get too much penetration on your welds and feel there might be leakage, fill the pan with water before you re-install it to check for leakage.
Not a difficult mod, just be careful and take your time.......also be a good time to replace the oil pump and the rear main seal if it is leaking.
Good luck.
