I too, am a fan of the HEPA air purifiers. Be sure to price the replacement filters because some of them are like ink jet printers - they are happy to give you the unit for free if it sucks you into paying a premium for their unique filter. Also you should be able to find one where there is a separate Carbon/large particle filter from the HEPA ($$$$$) filter so you can replace it more frequently with all of the dust you are getting in your house!
Just brainstorming - looking at alternatives:
1) Use it as an excuse to add a vestibule (kind of like an air-lock on a spaceship) to prevent dust blowing straight into your home.
2) Enclose the gear in a cabinet and add temperature activated exhaust fans like this:
Install a good air filter at the intake point and you can do something like drilling 3/8" holes on one inch centers to allow airflow where you want it through walls or shelves.
3) Add an underground sprinkler system on a timer in your backyard to keep the dust under control. When I worked construction at one of the local nuclear plants, they used water trucks to spray the dirt roads to prevent dust from getting out of hand. The trick is enough water to get things damp without creating mud-holes! If your dogs go out on a schedule, like in the morning and after you get home from work, then you only need to run it a few minutes before these two events.
4) Pea gravel in yard?
