We are thinking Spike might be a Basenji Terrier mix. He definitely has the basenji personality and the bark. We love him no matter what he is but we are curious.
The traits you described are also found in most of the Nordic/spitz type dogs. I don't see anything overly basenji-ish about him in the pics. What ever he is, he's very hansome.
Oh yeah, he looks way more like a b-mix to me than a lot of the pups listed as basenjis on Petfinder. And they mention he's not a barker. What a cutie! Someone go get this guy! :D