HMS Beagle, I really appreciable your post on this subject. Very informative and my experience with my 1988 Bigfooot is as you have posted. The only exception that comes to mind is the insulation and floor. My 1500 series Bigfoot has thinner (1-inch as recall) foam insulation in the walls and does not have a basement.
My vents have 2"x2" wood reinforcement around the holes. The back wall has 1/2" or 5/8" plywood on part if not most of it, at least behind the cutout for the door light/hand hold. I have not seen any wood around the windows or fridge door cutout, but I also see no need. I do have single pane windows. When look down the side of my TC, I see what appears to be weaves from framing. They are very slight, but noticeable. I am not positive they are framing shadows.
I am disappointed with extreme exaggerations some posters make. The result is most of their post have no creditably with me.
Wayne