Bryan, if you take that big rig down unmaintained trails, my hat is off to you!! My narrow little trailer is smaller than one of your slideouts, and there are many times when I make DW get out and walk in front of the truck to make sure we can tow the trailer into a tight place (and out again). Sand, mud, and snow are also issues -- not deal-killers, but things to be overcome with care.
I have tried to modify the trailer for off-pavement use (axle flip, heavy components, etc.), but I sure wish Arctic Fox made a little rugged trailer -- I would jump at the chance to own something like that.