One more question then, has he always been a "problem" barker at night, or is this a new thing?

If he has always barked at night then it probably a I'm lonely thing. The suggestions that I would have for that is to a) get him a little friend b) let him into the house where he won't be so lonely c) give him a good workout every evening so he sleeps through the night. If it is more of a recent thing then I would guess that he is uncomfortable. Maybe he is getting too cold. One other guess at this if it is new, do you have a new neighbor that has a schedule that he isn't used to?

On a side note, the neighbor a few houses away has a dog that barks for a few hours every night, I've contimplated killing that neighbor more than a few times and letting the dog live with me. It's a problem that has to be fixed