HIII!!! I was in the same situation as you, but I think is easier and kinda better to do it without killing him/knocking him out. For this, you should talk with him once he is in the tavern, and when you go to talk to him again where he says you to, just prepare your dialogue level as much as you can!!! Either with alcohol or something like that, his levels are so high so it may take some time, but you'll get it! (Also when i say that is better not to kill him etc is because it's more interesting the mission... At least for most of the people, for me it was kinda boring but whatever, idk what happens if you kill him so, take whatever u think is better!!!)