More Dust and Smoke Control Mods:
The passive Positive Pressure Vent has worked pretty well for me, but over time, I have had a slight accumulation of dust come past the bed rail, under the plastic bedrail cap despite obsessively plugging the bedrail holes in the Tundra pre-camper install. Not enough to complain about, but I also get some dust blown in past the barn doors when I use my compressor to blow off the back of the camper after stopping for the day or lunch. So I did this:

It’s 2 120mm cooling fans that are rated at 116 CFM mounted on a 10.4”x7.2x2.4" project box over the inlet for the PPV. I sealed the box around the PPV inlet and bolt holes. I like this company's boxes as they are O ring gasketed and used a smaller one for my electrical switch box previously. On Amazon as:
Zulkit Junction Box ABS Plastic Dustproof Waterproof IP65 Universal Electrical Boxes Project Enclosure

The box is pretty deep and it easily fits the dacron aquarium filter material I was already using. In the picture, there is also a sheet of MERV 13 over the dust filter that I was testing to see if I could also use it to filter smoke.

I tapped the 10awg wiring to my fridge and ran the power through an on/off switch and added a 3amp fuse. Both fans together draw an amp, and they are powerful enough to pull through both kinds of filters with a decent flow. I plan to not use the MERV 13 filter unless we’re camping and it’s smoky (I have a mild case of asthma) and on a routine basis just use the Dacron dust filter. I believe it will still work well as a passive PPV without turning on the fans, and I plan to just flip the side hatch when stopped and turn the fans on when I’m blowing off the barn doors to counter the blast of air trying to push dust in. Haven’t tested yet, but will be doing so in about a month. Will be happy to post more detail on the parts. etc, but trying to keep this post from being too long.

Since I had some left over MERV13 material, I decided to see if I could put it in the MaxFan. Real easy to do and as long as I don’t inadvertently set the fan to blow out can use it to filter air coming in. Won’t do this, except in a dust storm or smoke conditions if it’s getting too hot or stuffy inside.