Don't, in the best case it will take a long time before ipq50xx might get supported.
They aren't, they are using a heavily butchered up vendor SDK (QSDK).
Have a look at ipq807x (e.g. Dynalink DL-WRX36, I know, neither outdoor, nor PoE) instead, which are fully supported, everything would be a gamble with an unclear outcome (ipq601x would have a better chance (but still months+) than ipq50xx) or something Mediatek based.