During my recent relocation to Dallas, I invested in a custom cover for my SSR from Coverking, to protect it from the elements while it was parked outside at my temporary apartment for five months until my new home with a garage was built.
It is custom fit to our SSRs shape, made out of a durable, lightweight, waterproof, and breathable microfiber material called Stormproof. It rolls up into a compact package for easy storage in the rear bed. It also is available in colors to match your SSR with the option to add the SSR logo onto the cover. I actually chose non-descript gray in a futile attempt to hide my SSR in the public apartment parking lot.
I've been pretty happy with the cover and would recommend it. They are not cheap at $327 but are well constructed and fits like a glove even over the mirrors. The only thing mine doesn't provide is much protection from these nasty hail storms we get here in Texas. However, Coverking does offer other covers made from thicker, bulkier materials with more padding.