Stopping Dust getting into Van

What we have done to ours is to attach covers to all the external vents with velcro and press studs in the corners, this also aids in water crossings to minimize the amount of water coming in.
Easy on, easy off

mmm
you can get filter grade material of varing qualities
from foam to woven type media used in domestic airconditioning
then onto commercial grade of varing qualities & as a rule the thicker the better
then onto oil coated media which is almost top of range.

any media which is coated in oil has better filtration qualities

You just need the mechanics to hold media....

I suggest that your biggest problem is the vacuum though......

try one of these Site Link i have one on my van and never get dust in if i remember to open it hope this helps

len

Gday,
Try pressurising your van with air.
Blow air into it with a 12volt fan that runs through an air filter. I think you could buy them.
Cheers