We have a Adco Designer Series cover. It's excellent for protecting the roof & walls of the trailer from the elements of winter. I just posted a tip on the "Who's Checked On Their Camper?" thread. It's a great cover, but just take precautions to protect any sharp edges or corners that could catch or rub the cover.
"When the going gets tough, grab some cold beer, a good fishing pole and RUN LIKE HELL!!!"
2008 Ford Expedition EB, 5.4, heavy duty tow pkg
2013 Jayco Whitehawk 27DSRL