My 2013 Lariat has the Mytouch where it just acts as a wifi repeater, but it still uses your cellphone data and is kind've useless. I rather just use my phone as the hotspot and leave the Mytouch out of it.
As for the OP, I believe someone on here had Ipad mini kits where they modified the bezel and utilize their Ipad for everything. Then using your cell phone as a hotspot would work for Google maps or you can get an Ipad mini with 4G built in and just add it to your current plan. Then only thing that sucks about using Google Maps is if you are in an area that has poor cell phone reception, you won't be able to get updates when you need it. That's the one main advantage of a Garmin or built in Navigation is that it doesn't rely on the internet when driving in the boonies.