Pressure for low weight is much higher in EU due to the cost of fuel. In most expensive Norway gasoline
is 3.35 times more expensive than in NA, it is $8.86/gal
, ouch. This would be a wakeup call for NA RV manufacturers.
Travelling in EU I noticed that the travel trailers, the caravans have structurally engineered frames, like this one Caravan Chassis » AL-KO
to reduce the weight. In NA a couple of I-beams is good enough. Another example for weight constrain is lack of slide-outs, simply too heavy.
Gasoline prices in Europe 23-Oct-2017 | GlobalPetrolPrices.com
I think this is the material. a friend on another forum found this description. RENOLIT COMPOSITES - Honeycomb structure