I do see and plan to one day write up something for a Templar archetype for Paladin that is not Lawful Good, my problem has always been how best to replace Smite. Perhaps Smite the Guilty? It might even be better to create an alternate class, rather than archetype, since paladin is too defined with too long of a history in the game, to be other the LG.
Personally, I find that Paladin = LG to be so embedded into the D&D experience (and to be fair, one that I share) that for my own campaign world I've utilized Green Ronin's Book of the Righteous concept of Holy Warrior for anything not supposed to be a LG paragon of Virtue and the Holy Church. In other words, Paladin = LG.
Against standard military targets, including officers? Perfectly acceptable. But to target a specific commander, that's assassination. I see enemy sniping and specific target sniping as 2 different things.
Historically and certainly in modern times, civilian and military leadership disagrees with that position. Even in the case of specifically targeting enemy civilian leadership the available legal studies suggest that provided the legal requirements for war are met (such as a causus belli) then the targeting of a specific enemy leader, civilian or military, is legally justified.
As to an ethical stance, a common refrain from combatants, sniper or otherwise, is the idea that they believe that killing an individual, even one they specifically targeted, to be done in the belief that doing so would save their comrades.
For example, let's say for the sake of discussion that Robert E. Lee was responsible for the American Civil War lasting a year longer than it would have otherwise if the South had another general in charge of the Army of Northern Virginia *and* let's also stipulate for the sake of argument that the war lasting that extra year resulted in X amount of death, casualties, suffering etc. on both sides.
A case could be made given those two conditions that a Union sniper specifically targeting and killing Lee that year prior would have been doing the moral and ethical thing since otherwise he would have been dooming both sides to a further year of death, casualties, and suffering.
Now...what if the the Union sharpshooter taking the shot believed that to be case?
Of course, there's an another issue to be sure - in D&D worlds, Good and Evil are very tangible things; Gods typically have tangible effects, so as I argue, it will eventually come back to the group/DM as to how they answer the issues.
And I'm not sure there's a wrong answer.
