Yes, it's an OEM option but it's also a shared part with older F150's. Our van is a 2002 and I grabbed an overhead console and temperature sensor off a 2001 F150 with a similar interior colour. The F150 changed somewhere between our 2002 and your 2011 but the E-Series didn't so you should still be good to use one off an old F150. I mention this because there are a lot more 20 year old F150's in junk yards than there are Chateau E-Series vans.
You can find the sensor near the radiator on the F150 and there's an existing hole in our vans to bolt it up.
There are two holes in the ceiling that corresponds to the 2 holes in the overhead console.
In our case I had a very simple plywood headliner that I upholstered to match our build. The curves on the console didn't match, but I was able to cut down the high points to get a pretty tight fit.
No photos of the wiring but I believe it's fairly simple to wire up.
2 wires to the sensor, I followed a hole in our firewall that an alarm installer left behind. 1 wire to the ACC light (or whatever it's called) to adjust brightness and turn off when the ignition is off. I spliced off the head unit for this one.
1 wire to the VSS that I still need to tap. The console uses this to determine if the vehicle is in motion. If it doesn't get a signal the temperature will still work but it will only go down. The idea is that the VSS needs to return a signal that the vehicle is moving or the console thinks the increase in temperature is due to radiant heat from the engine/radiator. If it's moving it's getting "true" outdoor temp. If it's parked it's getting engine heat. In our 2002 the VSS is grey with a black line, and it's readily available in the bundle by the brake fluid reservoir. I just haven't had 30 mins to finish the job. (Typical...)