Hello, this may be possible for the PTP820S, but the PTP820C probably has too much of a draw to make this work in a 2+0 configuration. The PTP series is not technically standards based, in terms of power, but I have heard of instances where POE+ (802.3at) switches are used to power them on (PTP820S).
This forum post goes into some additional detail regarding POE options, mostly lower cost options that are used by our other unlicensed PTP products.
More interesting information available here for some specifics on POE requirements. Again, this would be PTP820S only.