Didn't know any test units were out there. This was about two weeks ago. I was heading home about 7:30PM from the lake house on a rural back road and it passed by me. Completely clear it was a 2015 F-150, NOTHING looked like this beast. It did not seems to have LED piping in areas I thought i would, but from what I could tell it was an XLT model. Had regular Indiana registered plates, no test plates or specialty plates. It was dark red with lots of chrome on the tailgate. Seemed really nice looking, though IMHO the design was a little larger and more awkward than I thought it would be. There was no camo on this vehicle whatsoever.
Come hang around Dearborn, they've been roaming around since the spring.
Guess that wouldn't surprise me, I thought maybe it was a test unit come out to play at the lake (tow boats or whatever). Lots of million plus people here. But it had Indiana plates rather than Michigan, that's the part that surprised me most.
On a side note, it was tagged with Indiana Personal rather than Indiana Truck, so legally anyways, it's towing would have been severely limited.