keep in mind that I'm a redneck from the southern US and I will shoot you if you try anything.
It's interesting that you would shoot someone for attempted rape. I noticed a while ago that I had a similar attitude, but when I stopped to think about it I realized that didn't make sense.
In general, it seems our culture has an equally strong reaction against rape as against murder. It's almost as if they were the same thing. But by any rational standard murder is far worse than rape. They're not even comparable.
If you really wanted to punish a rapist fairly, you'd get some big dude to rape him in the ass (of course don't warn him ahead of time, as the element of surprise and uncertainty is important). But you wouldn't kill him.
Of course I'm not saying that rape isn't a horrible thing to do to someone. But it's far *less* horrible than, say, cutting off someone's genitals or killing them. And, honestly, I think elevating rape to that level diminishes murder and other worse crimes. It's really quite disturbing.