I just ran into the same problem. Just bought a 2009 limited with 20" wheels.
I am a bit pissed at the dealer, we specifically talked about going to the snow and the need for chains or cables.
I have been doing a bit of research and found this product.
http://www.etrailer.com/Tire-Chains/TRS/TH02230K67.html
They are expensive, but look like the would solve the clearance problem with the strut.....
Urgh.....