See, this is what I meant when I said a few pages back that this thread was at its best when you just sit there and make up bullshit from start to finish.
To begin with, you'll see a man headfirst coming over the hill whether you're standing, leaning, sitting, or completely prone on the ground. That's why I said that question doesn't matter.
But I encourage you to do it one better. Why watch men come over hills when you can do it with buses? I'm really hoping you'll test this by going and standing in the middle of the road, then sitting, then lying down. Please tell me after that whether you see the tops of the buses first or the bottoms.