If you look at the listing for the CL21RBS (stock # 50793) at Nishna Valley Cycle in Atlantic,IA you will see a Livin Lite with fiberglass sides. I think that the different paint job may mean it is fiberglass. This one has the Platinum Edit but no enclosed and heated underbelly according to the salesman.
http://www.nishnavalleycycle.com/
I think I have seen one other Livin lite with this same paint job in TX somewhere.
The way to tell the difference between an Aluminum sided LL vs a fiberglass is the aluminum will have a seam 1/2 way down the side. The fiberglass will be smooth. I got this from a Dan Miller post over on the factory forum site.
Also....just for the record, fiberglass is an option. You can still get the standard aluminum sides.