Well I guess there isn't a clever solution out there 
Looks like I will have to stick to my routine for the other filters, airline outside on a rainy day and hope the neighbours are out lol.
caskwith,
The filter looks very similar to the ones used in my Earlex vacuum cleaner.
I put a dirty filter in a large clear bin bag with a brush. I then tie off the top of the bag and use the brush (holding it through the bag) to remove as much crap as possible. When the dust has settled I take the filter (and brush) out of the bag and then bin the bag.
I then wash the filter out in my sink in the workshop and leave it to dry stood on top of the CH boiler. I have two filters so there's always a dry, clean one waiting to go back in.
My filters seems to stand up to the regular washing OK.
I don't like the idea of cleaning it outside with an air line - surely you used the extractor because you didn't want to be exposed to the dust!

Phil.