loaderman wrote:Thinking you do not need red lines above the bottom of the fifth wheel area.
For 1 inch sq tube construction I would not be comfortable without some form of truss. The weight penalty for taking this out to the profile and having it perform double duty is minimal.
Being a hybrid foamie builder I guess I am not a full convert; I would want a "rigid" structure between the axle and hitch. Since the lines of force are broken severely by the coupler post to under loft joint (...which is also a concentrated load point on the center line, not out at the walls), and again by the notch in the underside of the loft to main body, the best way that I can see to handle the leverage and load concentrations involves steel. Rather than bigger sticks, I chose to spread the structure out, in theory saving weight.
If we were to consider doing this in ultra light foam with minimum frame, I would think that the side foam profile would need to be arched or curved at the transitions, and that epoxy/glass would be needed; both adding complication to the build. Since the OP said he was thinking small tube frame work, I leaned in this direction.
I had the same thought about curving the front (or faceting with mitered straight sections) to gain turning and pitch clearance with the TV cab, the whole front could be stealth bomber/geodesic dome like in construction for a really geometric look.
Again, all just back of the napkin thinking.