The key points which trip up paladins are ambushes, thievery, and non-combat killings (i.e. poisoning).
Having a complex about using oil or ambushes has nothing to do with being a paladin, IMHO.
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Ecgwulf, a paladin from a Viking culture (the name is from Beowulf).
I think for a classic paladin, honour is key. The reason for eschewing ambushes, thievery and the like is because they are dishonourable.
Which would apply equally to a viking paladin - viking law codes distinguish between murder - roughly, killin at night - and killing in a fair fight.
So if playing a paladin, you probably also want to think about what is or isn't dishonourable, and what other values are important to you. Honour was precious to vikings, but so was wit - there is a story in one of the sagas about a prisoner of war, waiting on the beach to be executed. He had long hair, and asked one of his captors to hold it out of the way while he was beheaded, so that it would not be stained by blood. Then, as the executioner was swining his axe, the prisoner pulled his head away, dragging the arms of the one holding his hair into the path of the axe, so that it cut of his hand. This clever deed was applauded by the onlookers, and the prisoner was spared and recruited by them instead. (Presumably the story is a fiction, or at least heavily embellished, but gives some feel for what the vikings admired.)
If an evil NPC surrenders, does the paladin execute them or free them (as I understand it, that AP will be doing things away from civilization so there are no jails and judges).
I think taking oaths and ransoms is an option here, at least for many NPCs - oaths to renounce violence, to do good deeds in repentence, to make recompense, etc.
Also it's important to know your DM's stance on paladin codes and what circumstances they will nuke your paladin status.
It's not unheard of for DMs to intentionally try to snatch a player's paladinhood, give them unwinnable situations/pit them against the party, or be very strict on how they interpret the alignment/code.
I wouldn't play with this sort of GM at all, and certainly not if I wanted to play a paladin.
Doing anything interesting with the paladin code, with taking prisoners, etc, requires the GM not to be a dick. For example, if the paladin PC takes prisoners, and extracts oaths of repentance from them, the GM shouldn't just have them turn around and rejoin the bad guys without thinking about the implications that has for how the player of the paladin can play his/her PC in the future.