The Orange Pi looks good, but it's a shame they have non-standard POE which seems to require weird hacks to make it work (https://parglescouk.wordpress.com/2017/04/14/getting-the-ora...). Having a single wire to each board would be very compelling if it could be more standard.
Are those solder bridges directly connected to the Ethernet Jack?
If so it would be much easier to just hook the 48V -> 5V step down converter there to avoid having to prepare a special Ethernet cable.