I usually try to take my water from the cleanest locations possible to reduce debris. 

That's a really good idea using stockings as a pre-filter.  It may however require some explanation to the wife as to why I am packing women's stockings for my camping trip...... ;D 
"No really honey, this guy I met on the internet said they work great...."

Personally I'm not a coffee drinker so I will likely just continue to backflush more often.  Great idea though.