What amazes me is that the distance of 60000ft (20km) is quite short here on earth. You can do it by bicycle in one hour. But if you go vertical, suddenly the rules change. Up there isn't even enough air to power the engines of jets, so the will have to carry an oxigen tank with them. If you go vertical things become difficult really quickly and space starts in vertical direction where the neighboring town is in horizontal direction.

Also, where is the limit when you would call the balloon a satellite? Satellites cross over foreign countries all the time, so there must be a height above which this is not a problem. Is there a fixed threshold for this?