Even camping in the train carts is a problem on insane, on level 50 that is.
One tiny blast from a grinder will kill you.
So basically, if there's a grinder around, it's only safe to blind fire.
If you don't camp in one place, I don't see how its possible by yourself, mainly at levels a multiple of 10.
bloodmounts can keep up with you, you're dead within a few hits, plus you've got the boomers and grinders trying to molest you.
sXe