I think the interior endcaps (with the built-in cabinets) are ABS, and lots of the bathroom but the coating on the inner aluminum is more like vinyl than ABS, and doesn't yellow as much as the ABS unless a smoker has been inhabiting the trailer. It is possible to peel the coating off the inner skins, but my impression is that it's a LOT of work.
Il Carriaggio — 1975 Argosy 24 | Il Progetto — 1976 Argosy 28 Center Bath | WBCCI# 15566
He has all of the virtues I dislike and none of the vices I admire. — Sir Winston Churchill