Yes that is two regulators all right. If I were to put in an extend-a-stay I would figure out a way to do it at the "T" fitting (The bottom of the T in the photo) this would require some serious adapters from the loacl propane supplier or some modification to the Extend-a-stay.
I wonder if Marshall Brass would make one special if you contacted them. I suspect they could but I need to take a look at my Extend-a-stay first.. Be right back...
Ah.. yes, it appears the male and female POL connectors are simply screwed into the main body of the Extend-a-stay.. This argues for their being removable and the unit being able to be installed below that "T". But talk to a propane professinal please.
NOTE: I've seen installs where they simply put in a "T" fitting and some manual valves.. These scare me.
Home is where I park it!