Yeah don't bother with the LV checkpoint in B42
I used debug mode with unlimited ammo, took me 40 irl minuteds of non-stop clicking, kill count is about 4500 and I'm sure there was more further away.
Definitely will not go there in a real run.
edit: For entering LV, simply bring a blow torch and dismantle eastern part of the fence away from the main checkpoint, it's safer and easier.
edit2: Tyler14827 says the shotgun kill count is currently buged so the actual number may not be that high.
edit3: Setting is apocalypse, I did it on day 7.