Hi Ian
You might want to look ak some of the newer Plastruct profiles. They have a more diverse selection of shapes and sizes which comes in handy when you reach the limits of Evergreen makes. They are a bit more expensive but they are invaluable when you are in a pinch!
http://www.plastruct.com/
I'd love to see your ARV!
Have fun!
Charlie
www.verlindenonline.com