You can bet that a sharp campaign will be checking the donor lists of their election opponent, and if they find fake addresses, it's not going to look good for the side you donated to.
A) Nobody is likely to check because of the size of donations that I make, and because I'm a nobody. B) If they did, the "Whoops I transposed digits" defense would work fine. C) I've been doing this for a couple of decades and nobody has tumbled to it. I imagine that there's a big pile of campaign mail in that vacant lot, however.