I'd first like to thank @Davidvr for his work on this. Tablo and Plex were really meant to be together.
I've got really close to getting everything working, but I'm struggling to play live TV. My server is on a different network than my tablo, so I've done an IP override. When I go to the Plex channel I am able to watch my recording, but when I go to my live tv I'm unable to play anything.
I see my channels and the guide data for the current program, but when selecting any item I receive an error: "There was a problem playing this item." My router has the tablo connect ports and port 18080 (read this in a forum post somewhere) forwarded to the tablo.
Does anyone have ideas?