We take our two outside and blow them out from the inside. Blowing them down from the outside does very little in my experience
I never find it too nasty. I just run 100 psi on the hose and I just plug in a coupler nipple and shove the hose down in the inside of the filter. The air hose acts as a whip (gentle) flops and floats around the inside bumping/shaking the pleats as well as the air and its blowing all the dust out the other end away from you. I do that for a while, flip the filter around, repeat, and repeat, and repeat, until pretty much no dust. Been doing it that way for years and never hurt a filter. I do have a bit of a lucky situation in that infront of the bay that has the DC's in it there is a road grate that runs down under the road to a culvert across the street and I stand the filters over that grate and blow all the initial dust down into the road grate. In short order there is a sawdust plume 40' across the road. But once they are pretty much blown out I just hold them at an angle and flop the hose/coupler/nipple around inside the filter.
Its not terribly bad and well worth it when you hear the DC roaring again pulling massive amounts of air because you should have blown them out a month ago.
I back flush my filters and duct the exhaust dust outside. I have to wait for a west wind because my wife got upset when the wind blew the dust over the patio.