How to play music via USB and have Carplay showing map at the same time?
 

In short, can I play music via my USB stick, not my iphone, and have the screen display the Map app via Carplay?

The lengthy story:
Hi all, just got my 2017 Civic EX and I am having a little trouble.
I want to play music via my USB stick (via the USB port in the cup holder area). I plug the USB in and it can play successfully when I select my audio source as USB.
However I want to have the music in the background, while I use some sort of map. The most straightforward map is using Carplay to use my iphone's Map application. The problem is whenever I switch over to carplay, the music from USB stops and I can only play music via my iphone. My iphone is 16G so it doesn't have space to hold music.

I have tried googling and opened the can of worms on how to root the display and try to install Navigation app...etc etc which I still haven't really figured out the steps yet.
Before I go any further down that path, is there anyway I can play music via my USB stick, not my iphone, and have the screen display the Map app via Carplay? Kind of like having music program playing in the background, while the screen is showing maps...

Thanks in advance!