Griffon,

I would never design a frame so that I can apply a certain layout design. Design your frame and then figure out how to lay it out. Traditional is not always the best way.

As far as SIPS go. They would not be used for interior walls anyway.

If for a minute you forget about the traditional english frame and think about what it is that you are trying to build than you come up with a number of ways to achieve a very stable stand alone frame. If you try to apply this to the english frame you will consequently run into the same issue over and over again.