1) Establish how the Walkers work on all levels. I know the writers don't want this because it will hem them in storywise. But it needs to be done for the good of show. Last season our heroes had to cover themselves in Walker guts to avoid detection, now they just duck under cars and put Walker bodies on top of themselves?
They also had to walk directly past the walkers during the scene from season one that you're referring to. Here, "out of mind, out of sight" so long as no blood and no sound occurred was enough, and I don't see why pulling a dead body on top wouldn't work - it's still the same smell issue as before. See a previous post of mine for some of Robert Kirkman's thoughts on this.