I live in Tucson, and pretty much follow the same routine as JCHer. Regarding the plastic parts. I mask them all off, and give them a coat of white Krylon plastic paint. It seems to protect them very well against UV damage.
I tried covering the unit, but the hassle of covering and uncovering it just wasn't worth it. If we wanted to take off for a weekend, it was a pain to uncover it. Then, when we got home, we were usually pushed for time, and had to struggle up the ladder to cover it back up. Then the wind got ahold of it when it was about 6 months old and shredded quite a bit of fabric. We tossed it in the dumpster.
One area of sun damage I just dealt with was the awning. The fabric that was exposed to the sun was brittle and delaminated. I had to replace the fabric. But this unit has been sitting in the sun for seven years. Not too bad.
2016 Ford F350 Turbo Diesel SRW 4x4
2017 Grand Design Reflection 297RSTS
2013 Ford F350 Turbo Diesel SRW 4x4 (Destroyed by fire - 8/29/16)
2014 Grand Design Reflection 337RLS (Destroyed by fire - 8/29/16)