We cover ours in the winter, they may be designed to be "outside" but anything you can do to keep driving rain and/or snow out is a good thing IMO. Not to mention keeping UV exposure reduced.
Definitely get one with zippered panels.
2013 Starcraft Travel Star 229TB
2011 Jayco X17Z(traded in)
2010 Jayco Jay Series 1207(traded for the 17Z)
2011 Chevrolet Silverado 2500HD Z71 CC 6.0L/3.73
Reese "Pro Series" 800lb Trunnion WDH w/sway control