Im speaking to composit panels. Not a camper, with lenolium flooring, various window products, appliances, heavy plywood lower structures etc.My wood framed campers are not heavy. I can promise you that.
IDACAMPER2.0 is a 10' flatbed, 4-season model, and weighs just 2200 lbs dry.
Similar 4-season units using other methods of construction are considerably heavier.
An Artic fox 990 for example, has a dry weight of 3010 lbs.
The campers your using as examples are big campers were weight is really secondary to accomidations ment to simulate a sticks and brick house. In the sailboat world we call it hauling the furniture. When you fill a structure with skinned ply furniture your not concerned about weight one bit. If you were there would zero wood in the build. Example XP campers does engineered composite campers the interiors are composit pans, light and strong. Labor costs result in $75,000 $80,000 campers, vs 30k wood frame aluminum skinned campers.