I just received the latest issue of Flying magazine. Lane Wallace wrote a column (I think the title is "The Real Deal") about a visit to the National Air and Space museum. The column started out with her tour of the facility where all of the Apollo moon space suits were stored. Despite all the cleaning efforts, the suits are still stained from the moon dust. The curators said that nothing they tried could get the fine dust out of the fabric. That being the case, your idea might need some work. Unfortunately, Lane's column isn't available online yet, but it should be available here next month. She's a wonderful writer.

Now, it might be possible to come up with a better outer covering that is more resistant to dust. Perhaps the covering would be replaceable, or perhaps it could be very smooth so the dust couldn't get into the fibers. I saw a news segment yesterday about British efforts to make chemical resistant military uniforms. They used a cold plasma to put a thin coating of something on the clothing, making it completely water (and chemical) resistant. I don't have a link to the news story and I don't remember what they used for their plasma, but the idea seemed to work rather well.