Nope. No uncertainty. If I'm really blind, I'll wind down my windows and listen for cars coming close. That is, if I wasn't able to back into a spot for some reason. But I back in like 99% of the time anyway.
On the highway, just be careful. Look twice. And if you make a habit to drive faster than everyone else then it doesn't really mater, does it?
Just saw DR's comment. So there's two votes for driving faster than everyone else.