My son hit a moose and did some damage to the hood and grille. There was a couple rust spots so I thought lets fix it & paint the truck. The body shop welded in about 3 patches. About 3 years in and we could see the outline of every patch showing themselves on the way to breaking through. Water is going to wick in the butt joint if they are not sealed. I live in Canada in an area where some times the salt blows off the highway like dust when a transport goes by. My friend and I repainted his old Ford van. I made up patch panels & prepped them for tight fit ups to butt weld. We had a welder friend weld them in. The van looked great in Cadillac silver & charcoal. The patches looked good until the van died. I would go with a butt joint if it is possible.