As some of you know, my day job is working in a commercial shipyard. As such, we tend to be painting rather large objects that can take literally hundreds of gallons of paints, and they are all done outdoors. We actually have to maintain logs of how much VOC we are releasing weekly.
How do we do it, you ask? It's simple; airless spraying. We use air powered pumps that output paint at several hundred pounds of pressure, and use special guns with no air connections. There is almost no airbourne paint, so we can get away with just tarping over a vessel (which can get a bit involved; imagine tarping over an LCU that is sitting on dry land about 10 feet off of the ground!)
Granted, the cleanup is a bear; you have to be very meticulous with the pumps, lines and sprayguns, particularly when you're shooting a catilyzed 2 part epoxy that will fire off in 3 hours, and you have several thousand square feet to cover with 15 mils of wet thickness, but it can be done without sags by a good crew, who will get all of the equipment cleaned up before disaster strikes.
I honestly don't know if there are personal versions of this technology, but it sounds like there might be a market for it soon!
Marty