In Sensorly, I see LTE activity just north of Homestead Air Reserve Park, mostly on the Turnpike. The LTE may be switched off for now, as I went through there a couple of hours ago and didn't pick up LTE.
With Sensorly on, I drove south on SW 137 Ave from 152 St until I reached SW 168 St. Drove east on 168 st until US-1. Drove south on US-1 until I reached the southernmost entrance to the Turnpike, near Palm Drive. I entered the Turnpike and drove north, exiting at SW 152 St.
I'll have better luck next time.