We replaced the regular vent & fan in the toilet room with a fantastic fan. It was not rain sensitive or automatic. It can blow air in or out. The one in the kitchen only blows air out.
We also have a fantastic fan on a thermostat in the kitchen area and it will close automatically if it starts to rain.
We put a MAXX Air cover over both because of how the wind will break the covers and to protect against both wind and rain for the one in the toilet room.
I like to open the vents in the summer while going down the highway to help keep the interior a little cooler aiding in cooling it down when we arrive at our camping site.
These vent covers are larger than the regular ones allowing the fan to open higher and move more air.
BC