Several companies offer a vent tube cap that eliminates the problem of bugs and debris. Both our motorhomes had these caps installed on the vent tube. I assumed they came from Ford, but looking for a Ford part number has so far been unsuccessful.
They may have been installed at the Winnebago factory, at their service center in Forest City, or by our local Ford garage. I suspect the latter in that this dealership also sells Jeeps, and the caps are almost identical to those on the vent tubes of our Jeep Wrangler.