Another plan for the kingpole

For the large round pavilion (what we've called the NorthStar) Chris suggests that we might use two 4x4s, with a steel pole sunk deeply into one end of both of them, to create a joint. This would have the advantage of reducing the overall length and weight of individual parts.

Would this reduce the integrity of the kingpole? Can we drill a 1" or 1.25" hole deep and straight enough into a 4x4 to make this viable?