Great! You have a Smartphone! Maybe you're not as low tech as you mentioned. It's been a while since I experimented with this stuff but I don't remember trying to plug in my phone to the 3.5mm connector in the left fairing. Seems like that would work though. What I have done is to power my phone with a cigarette plug/USB socket in the left fairing cubby and BT link that to my Sena 20S headset. That does work quite well. And, BTW, my Samsung Galaxy S7 Edge is weather-resistant.
I can't emphasize enough how awesome the WAZE app is on your Smartphone. Not only does it handle navigation like a GPS but it also alerts you to traffic conditions, cops, and obstacles in the road. I'm definitely a WAZE fan!
As you will see from other comments on this thread, there are various ways to get what you're looking for.