I'd like to add something to this thread that worked for me.
I used two 1/4" x 1-1/4" neoprene washers to fix the taillight alignment issue on my car. They're super cheap, and super effective. You will need 4 washers, or 2 packs.
1/4" x 1-1/4" Neoprene washer.
Put one on the rounded locating post where the taillight 'wing' is, and the other on the forward-most threaded mounting stud. The washers will space the taillight out enough to prevent contact with the body, and also prevent any squeaking/rattling that a solid metal or plastic washer might induce.