At this point, all of mine are uncovered boxes (and they are the HUGE long litter boxes that PetSmart was selling) except for the litter box in the kitchen. That one I cover just because it's in the kitchen. It's there for Furbee and Boris in case they are too intimidated to deal with Zach to go upstairs (there are times...).

Unfortunately, I always have someone who misses pooping or peeing in the covered box. It's the biggest there was, but they go in face first, and then poop, and unfortunately, their butts are still outside the box, lol. Gotta love it!

I know at the shelter we never use clumping litter with the kittens. We use clay or pine. I wouldn't worry about Paizly at this point, and I'm sure there are millions of people who have used clumping litter with kittens and they were fine. Don't feel bad!