I finally decided to do a total pacifist run of New Vegas. All DLCs complete except for OWB because I couldn't be bothered with it. Here are my stats right after dealing with Lanius. It's not exactly a completionist run but I did every quest I came across. It was a lot easier than I thought it would be, the game really isn't that combat heavy unless you rush out into the wilderness and walk into a cazador or deathclaw nest or something.
The rules I set for myself were that I couldn't use companions to kill people for me, I couldn't lure enemies into friendly NPCs to kill them for me and I couldn't do that lame-ass trick where you shoot weapons out of people's hands and then run away. I did end up non-fatally injuring a bunch of people with the boxing gloves and cattle prod but they're basically useless because the knockout time is like 3 nanoseconds.
I indirectly caused the deaths of only three people - Caesar, Motor Runner and some generic idiot who tried to fire a grenade at me and managed to blow herself up with it.
The game also becomes a total joke when you get 100 Sneak.
Only time I had any real problems were whenever I had a companion with me, which was very rarely, because they go apeshit and murder everything in sight. When I was taking Boone around with me to do his shitty Bitter Springs quest I had to repeatedly knock him unconcious just to be able to move around the Wasteland without getting into shit with someone.
The other part that sucked ass was Dead Money because not only are you forced to take companions through the villa with you, but their kills are actually counted on your own kill counter which doesn't happen with regular companions. On top of that, I'm pretty sure any Ghost People casualties were attributed to me whether I actually did anything or not because the game blamed me whenever they walked into traps or blew themselves up, so it ended up taking about 5 billion reloads.
Anyway, I knew that a pacifist run was possible and I know that practically every quest includes a pacifist option but I still couldn't help being impressed at how easy and natural this playthrough felt. It'd be a huge stretch to say that the devs intended you to try a pacifist run but the game definitely accommodates it.