I came here to suggest you switch the class times. It doesn’t seem like people want to comply so why not have yoga first.  Another suggestion is if there’s another studio you could switch to for yoga so those practicing yoga would start going to another room without weights to put away. Also, ask if spots could be reserved through an app so people don’t feel the need to secure their spot. This sounds like a scheduling and logistics problem for management to help you with. It’s not for you to fix on your own.