Thanks, Cliff, David and J.
That is a beautiful wooden outfit! As for eco-friendly, it depends on the wood treatment and finish. I don't want to use anything that will give a lot of out-gassing volatiles. But I've been thinking about wood lately, since I read that moisture can be a big issue in Airstreams. Wood will act a bit of a moisture absorber, I would assume, to a certain extend at least.
J., what wood/ply did you use to get these curves?
The shower bench is a great idea. It would be difficult to get an original Airstream mould to Australia and I already have a small new bathtub (120cm x70cm). It's enameled steel, which is maybe a bit heavy, but it could just fit between rear bed and the wheel cap!