Yes, spot clean and once a week stir in the urine. In "The Art of Keeping Snakes" the author suggests that stirring in soft poop from smaller snakes could work and that he has had some success doing so with his water snakes. I have also read from others on Gecko forums that it is possible to stir in poop when keeping Geckos as long as you have a "cleaning crew". A cleaning crew consists of springtails, isopods and sometimes earthworms. The cleaning crew will break down the poop to a state more manageable for the natural bacteria to break at a rate that can keep up with the animals.