I have covers on all three roof vents. MaxAir on the two normal exhaust fans and a special one for the Fantastic vent. Camping World sells them for both fans (the Fantastic vent is designed to allow additional air flow for the fan and costs just a few dollars more, slightly different shape but colors are the same). If you're in Good Sam, they'll even install them for about $15 each which was way cheaper than me breaking my neck falling off the roof!
2015 Legacy SR340 360RB
2014 Jeep Wrangler Unlimited Toad
Gigi, Poppy and Sadie Lady...On the road, but not full time!