Salsa Fargo is the biggest off-the-rack touring bike I know of in the US market. The headtubes are very long. "virtual seat tube" on the XXL works out to 72cm, with a 61cm top tube and 72 seat angle. It's actually a less reach than I'd like with drop bars, but beyond that you're in custom frame territory (or import something expensive from the northern Europe market) I'm afraid.