I appreciate the points that have been raised, and I am realizing I am going to need to hone the design criteria and get as specific as possible to achieve the goal.
I have decided NOT to go with a custom tube frame solution at this time, purely because of cost. I do stick by my original design ethos, however, which is an engineering study in lightweight materials. For example, Starfire systems makes a bullet proof panel that is highly insulating and extremely lightweight. These are the panels used on Space X Rockets, etc. They are Ceramic-Forming Polymers, (Polymer TO Ceramic). A single panel does multiple duty; structural, insulating, friction / abrasion resistance, even bullet proof. A single coating of Arovex carbon-nanotube epoxy on the outer shell will increase strength even more while adding very little weight. I hope to have a wet-bath built out of Arovex as well.
***Now, if we consider other methods of construction, even water tanks can be molded out of "fiberglass", which in this case would be Arovex Carbon-Nanotube Epoxy. If I were considering making a large RV or a Sailing Catamaran, I would look into creating bulkhead "cavitations" in the resin moulds, in which a heat resisting coating could be sprayed, and then molten titanium foam poured and allowed to cool and harden. This, while being incredibly light, would also be incredibly strong. On a camper the size I am considering, such metal foam bulkheads would work great for something like an overcab bed.
Now, I admit I have to do a full cost / benefit analysis on these materials and make sure the builders know how to work with them. That all raises further price concerns.
I am working on preliminary designs, and when I have something to show, I will post it up.
I do stick by my original claim though, which is, for example, if the XP cube was made with Arovex Epoxy instead of the usual yacht grade stuff, it could lighten the weight of the shell by 50%. If the furniture was made with Arovex, similar weight savings can be realized.
I do realize there are other trade offs that must be considered; for example traveling with a companion increases weight exponentially, because of all their added gear, water, etc.
So, perhaps the Raptor is not the ideal platform. I haven't come to any conclusions yet. I DO know that I want a GO-FAST camper, something you can pass with on the highway, and something that will get you pretty much anywhere off road.
I need Heat, wet bath with a Cassette Toilet, all tanks and plumbing must be INSIDE the camper to prevent freezing. Breville "The Smart Oven" or Panasonic Infrared Toaster Oven INSTEAD of a microwave. Butane Stove. Uni-Solar Lightweight Adhesive Solar Panels. Lithium-AIR Battery Bank. Ideally I would like to have a rooftop Rainwater Catchment System.
All of the Auxiliary Gear will also be super Light Weight. Including "Zero SR" Electric Auxiliary Motorcycle.
I am dedicated to this "Discipline of Ultra-Light Weight" by any means necessary, and I realize there are significant engineering challenges to get there. But I have at least a year before I will be ready to begin construction, and much design work can be accomplished by then.
I would be happy if this thread became the "go to' spot for discussions of Light Weight design, or perhaps a new one should be started with that intention. But I am sure I'm not the only one thinking about these things. When I say "light weight" I mean even down to Titanium sporks. EVERYTHING light weight.