I would think (as mentioned above) the biggest obsticle to making that change is mounting the shackles to the trailer. Airstreams don't have a traditional frame set up. The frame is lighter because the body is intergral to the whole assembly. There for mounting a spring shackle to attach the leaf springs is going to be an issue given the make up of the frame.
I am personally of the opinion that a leaf spring set up would be better mix for me. The ride may be not as smooth, however the design is cheaper. Just don't think it's gonna work on an Airstream.
1966 Mercury Park Lane 4 DR Breezeway 410 4V, C-6, 2.80 - Streamless.
1966 Lincoln 4 door Convertible 462 4V 1971 Ford LTD Convertible 429 4V Phoenix ~ Yeah it's hot however it's a dry heat!