Hiker Trailer is now adding netting in the AC vents. We are no longer making these but if you are interested in making your own covers, you can find the file here: https://www.thingiverse.com/thing:7062575/files#google_vignette
 
This cover will let the fresh air in and keep bugs and rain out. 3D printed and made from PETG, they have been tested for 2 years on a Hiker Trailer. The net is replaceable using a snap ring design inside if the bug net would get damaged. The covers come as a set of 2. This doesn't include the 90* elbow. Recommended accessory would be the 90* elbow from Valterra.