The Sport 10 PUP I had came with a roof vent with the MaxAir Cover. So I'd just crack the vent open a tad and left the unit closed up otherwise over the winter. Did not have any issues with water or moisture buildup.
Wayne, Kim, Mallory & Abby the Dog
2013 - Jayco Jayfeather - X20E
2012 - Toyota Tacoma DBLCB Sr5 with towing package
Equalizer 10k WD, Prodigy P3 Controller, TST TPMS
2012 - Jayco Sport 10 Popup - Traded