I removed the BMW Navigator III from my 2007 LT. Once the cradle is removed, you're left with a great blank panel for mounting a smartphone. The panel is plastic, but behind it is a metal mounting surface already drilled and threaded for an AMPS plate.
My simple-as-soup solution was to buy a shorty RAM arm and two RAM-ball AMPS plates, then I added some Velco and the phone is mounted! Here's the mount--
Here's what it looks like with the phone mounted--
For power, I'd already removed the left panel intercom port and replaced it with a Powerlet power port. I plugged a Powerlet-USB dongle into the port then plugged the USB cable from the phone into that. The Powerlet port gets its juice from my switched aux fuse panel under the seat.
While I was messing around, I also added a TPMS that uses transmitters that mount to the tire valve stems and a receiver with LED display to the blank panel near the left mirror--