[chris mc bride]

IMO and Im by no means a body man.The lap weld will be best because it sounds like you have limited experiance with a welder.I will just be easier & I agree stornger.A butt weld should work fine but it will take a better welder to weldit w/o blowing thru and havine to fill the holes.Like I said it just my opion,not body man but been welding fuel tanks for custom bikes for years and if theres a good teacher its the super thin metal used on tanks.