B.A., the amphib you just described makes a LOT of sense. I have been distracted the last couple days on an idea that I cannot get to come together. Your idea would fit within the 1,500 pound limit required for offroad use here in AK. (Does anyone know what Canada's rule is for offroad vehicle weight?)
I have been thinking about the X craft catamaran the Navy built, and trying to sort out an all track driven catamaran design, but I am having too many "if"s about it. The goal there was to make an amphib that had sufficient speed and low enough drag to allow for crossing Alaska's cold and treacherous rivers.
I love my Argo, and I think your idea has so much working for it, but even with an outboard, a machine like that does not cross serious rivers. I am not stuck on crossing fast rivers, but it is a niche that has not really been answered yet, and would make playing around in the interior of Alaska exponentially better. A large 6x6 with that good old low CG, but very high sides would be appealing. A little bit of math could make a machine that you can still see over the bed of when looking backwards, but that would let you stack meat low, and then lighter cargo high, and make the meat wagon tow behind completely obsolete. That would do us some good here in the interior. 6 axles would have to be quite robust, because they would likely be called upon to transport over 1,500 pounds.