Hmmm... Do you have a brush attachment? There is also an attachment that is designed for draperies and curtains, the one I remember seeing/using was a wide-head, about 5 inches long, and the "suck" end had a row of thin slits instead of just open or a brush. It was more 'gentle' in sucking than other attachments or just the open hose.

I bet you could engineer a special attachment *wink nudge*