Well this is not the way to ask for a feature - by using an api that was intended for different scenario. As I said a refreshReachability will get the same result once the port number has been set to zero at plex.tv end. It will only change if the user goes through the steps of disabling and re-enabling remote access or possibly restarting the server - or some periodic action by Plex Media Server. The end point being used is there for plex.tv to use when the user configures remote access and enables it and the user would be on that settings screen.
There are other means for Tautulli to achieve what it wants to do. One example would be to request the machine identifier from your server via GET /identity and then use the identifier to lookup the non-local entry for that server within the resources.xml for which the end-point is already published in this support article https://support.plex.tv/articles/206721658-using-plex-tv-resources-information-to-troubleshoot-app-connections/ . From the resources.xml, Tautulli can get the url to use to reach the server through the WAN public IP.
Of course hitting plex.tv with such a request every minute from every server with Tautulli would be unacceptable and could be seen as a DDOS action - but doing it every 60 minutes may be ok - but the volume of servers doing it would need to be assessed by the Tautulli developers and perhaps negotiate with Plex to allow for high volume of requests which Plex may not have allowed for when sizing the plex.tv infrastructure.
As to features, beta 1.13.5.5291 which was released a few days ago brings in a feature that many users have been asking for and waiting for - Bind to specific interface only?
