My entire network is Unifi based and I cannot think of a way for you to accomplish what you need. Maybe if you had a smartapp capable of logging into the switch via SSH and sending the appropriate commands… but that is likely too complicated to do for this.
Before I adopted Unifi, I was using this POE Injector, which has an ST DTH:
This would power your POE devices and allow you to turn them on/off remotely. A side benefit is that you can hook up backup batteries to it to power your cameras during power outages. I am not thrilled with the quality of the build but it did its job. Mine is now collecting dust… maybe I should list it on ebay.