I keep mine at a storage lot with a metal roof for covering. My 303 is, however, exposed to the morning sun at the front and afternoon sun at the back. For this RV as well as my last one, I ordered custom sized shade cloth (90% blockage) from the Greenhouse Megastore. I fasten the shade at the four corners using the installed eyelets on the shade cloths and cord with tension adjustments typically used to pitch tents. The shade cloths are reasonably priced, lightweight, good warranty, and they are great for protecting the gel coat and graphics from the sun. Of course if you unit is totally exposed to the elements, you will need a full cover. My neighbor used a full cover on his 37-footer for several years but the Texas sun is brutal and required him to replace the cover every 2-3 years. This eventually led to oxidation and de-lamination. He's polished out the oxidation, repaired the de-lamination, and now keeps his unit in a totally enclosed facility.