As a former "lifeguard" pilot
As a former "lifeguard" pilot I can just point out one thing, I am not going to kill 3 to "save" 1". If its dark and I can't see the terrain, runway environment and there are no lights - I am not landing, I don't care if it's 91, 135 or 121 or whatever, unless it is a true emergency.
I can remember a time when I had to fly into a strip near a clinic at night, an old guy would come out and start a generator at night and it would run the lights. Once they couldn't get it started and I wouldn't land (King Air on a 20' wide strip, 2700' long). The clinic got mad, called our competitor and they put their 421 into the ditch landing - pretty pointless. It was frigging black as hell. Yes, I flew in the mountains, in the bush, off dirt and mud and in awful weather, but I wanted as many outs and resources as possible. When you are as much of a hack pilot as I am you need everything in your favor.
As someone else pointed out, the insurance company is the last word in many cases, wreck an expensive piece of machinery doing something stupid and guess what - they won't pay.
A friend used to say - when considering something outside of a "normal operation", picture yourself in front of a jury, judge and the family of your pax that were killed or injured if something went wrong, even if it is not the fault of the stupid act, and you should be sure that you can, truthfully, say that "I, as a professional, did everything I could to make that fateful flight as safe as I could, using the industries best practices and procedures and in compliance with all regulations (and the intent thereof). And I am truly sorry, I did everything I could."
Fly well.