I'd get a used 870 from 10+ years ago (the newer ones aren't as good as the old ones). Get an 18" barrel for it and be done. 5 rounds is standard but you can extend the tube magazine if you like. With the long barrel back on it and choke tubes, you still have a nice gun to take bird hunting when you come visit me.
If you want to get fancy the Benelli M2 tactical is a very nice gun as well. Not sure if I'd spend that much money on a defense gun. For the field (M2 field) maybe ...
G