Without getting into the "necessity" or lack therof of either item.....DONT buy them up don't at that cost. It's easy, look at what they cost to buy, easy. Decide if they're overcharging you. Likely.
It's called up selling.
Now getting into the items. I'm not an experienced RVer like most of you all, but I've driven our camper through most imaginable weather conditions. Like getting chased by tornados and lime most, have camped in torrential rains. Never seen any water intrusion and for my purposes vent covers aren't necessary. Winter storage? I suppose if you store out n the open with no cover on the rv, then maybe. But my sled trailer sits out 24/7/365 with vents open in W WA. Never seen water inside from the vents.
Topper. Have had 2 identical campers one with, one without. Old one without didn't leak water in, but I did have to sweep off the slide when parked in the woods. Also sweep off the topper when wet leaves stuck to it. Those awnings stay wet when rolled up, slide out will dry itself off. I only see advantage to those in the snow.
