Will my male jack russell mix get along with a female jack russell?

I have a jack russell bett hound mix and am thinking about getting him a playmate. He's 4, neutered, housebroken, and isnt that hyper. I have been searching for dogs younger than him and smaller so that he can still be the alpha male. If I got a female, spayed jack russell full blood do you think they would get along well after a while? I just know that he is very territorial with other male dogs, but females dont seem to bother him. Before I got him he lived with 4 other dogs, so I'm thinking he is missing his playmates. Does this sound like a good idea?