A schematic may be useful to other helpers.
@robotwhispering
I'm not familiar with how exactly POE does its thing. And, even if the specifics say it should be isolated, you don't know what costs may be cut in your module.
If you want to be 100% sure, you can try to roll out your own solution.
Since it is a remote location, i would suggest doing it similar to the mains grid - generate higher voltage (but not too high to be unsafe) AC at the source, send that through a separate cable (you said you can consider running another cable), then rectify and stabilize it at the destination.
What distance are we talking about?