Ours was fine parked outdoors year round.
No cover for the summer, but washed the roof well a couple of times a year to keep it tidy. In the winter, we parked under a very large pine tree at my mom's. We would tarp it for the winter primarily just to keep the needles and sap off. If you tarp, just be sure it is a good quality tarp that won't bleed onto the cover. After 7 winters, there is very little wear on our tarp.
Many people shy away from tarps, but our experience has been good.
One advantage of the pop up is that the roof is very easy to check for damage or leaks. Ours needed a bit of fresh sealant on the edges at the end of 7 years, but was relatively easy to maintain, and there was no fading or weather damage apparent.
2011 Jayco X19H (purchased 2015)
2008 Jayco 1007 PUP (purchased new, traded for the X19)
2012 Chev Traverse LT with TP