I was thinking the same for my new camper. I was going to buy a house air filter at home depot, cut it down to size and possibly hot glue it in, I thought it could definitely breath but was skeptical on the heat being able to escape...any thoughts????
One trip to Baja and the whole refrigerator area would be CAKED with dust.
Somehow that idea just doesn't sound good. Maybe you'd consider making a cover for the vents while on the road, and not using the fridge??