How long do you guys think I can wait until washing the towels that will go in my playpen - made up of about 10 storage cubes? There will be two boars playing in it everyday for about an hour or more. Using the washing machine to wash the piggies stuff (even in a pillow case) isn't the best alternative for my family. We're not quite agreeable on that. I think I'll just thoroughly hand wash it when it needs it. I'm just wondering how often you guys think I should clean the playpen towels?