If you do not get this in the campaign level, you can set up a custom match with the AI. I selected Wermacht and the commander that had the Tiger Ace perk. Set up a 4 vs 4 match with all easy AI opponents and once you have enough to call in the Tiger, just park it near the center control point with some infantry support and some engineers to repair and you should get it no problem. My Tiger had 78 kills at the end of the match. It will pop mid-match once you reach 50 kills so you don't even need to finish the match.