If you love kids and have a little extra time on your hands, Christy Stocker might have a job for you. As principal of West Marin and Inverness Schools, Ms. Stocker is finding it increasingly difficult to hire substitute teachers, even as the need has grown in the aftermath of the pandemic. It’s not too difficult to get registered as a substitute—assuming you have a bachelor’s degree and a clean record. The Marin County Office…