Gate stability | Problem Solving | Forum

In the 3rd quarter issue of Hot Iron News 2014 there is a great article on the 4 hour gate demonstration of Terry Carson and Darryl Nelson. I was not lucky enough to see it. Really a nice design executed by two of the best. 

Part of the demo may have discussed the stock size, particularly the outer frame. From the photos it looks to me like maybe 1 1/2 x 3/8. My guess is that the type of banding joinery used at the top of the frame may require a thicker surface between pieces to be more secure but I am not sure. Can anyone offer info on this?

I also wonder about the flex across the whole plane of the work. It may not be a big issue since the gate appears to be about 3ft. tall, but it may be a more important consideration for a taller piece.

I would like to use this outer frame design, copycat that I am, for a new entrance to a part of my property. One of the main differences is that I would like my gate to be 6ft. tall. Beyond that, it would not use the very nice scroll design to add lateral stability. In this regard I am looking for other stabilizing strategies that don't change the esthetic much.

I sketched a design. It may be helpful to understand what I am asking. Thanks, guys and girls for letting me pick your brains.