The issue isn't POE, it's cable length limits. In very general terms, your limit is around 328 feet (100 meters) per run.
You're not wrapping these things around the building, are you?
Assuming worst case, you can half-split the distance by placing your POE switch in the middle.
If you plan on using this network for more than just IP cameras, I highly suggest you place the camera network on its' own VLAN. That way, you can limit beaconing and potential compromise.