This is how mine is mounted. RAM ball connected to clip-op tube, 3" RAM double ended adaptor, base plate mounted on RAM ball.
I've got my iPhone mounted on a Quad Lock system. Rugged, sturdy and solid as a rock. Also has a brilliant waterproof sleeve to run over the top which fits like a glove. Allows me full road pilot live and TomTom maps to run in sync. Just need a Bluetooth headset to hear the alerts. An anti glare screen protector means its as clear sat on the bike in the sun as the digital dash