Room-Assistant as replacement of the Bluetooth LE Tracker integration?

Hi there! So i have owntracks and cloudmqtt setup with my phone but as many others i feel that the discovery is taking a bit to long. I’ve found that home assistant can be set up to track phones via Bluetooth LE and should be working much faster. Although this intgration doesn’t seem to work very well either according to reports.
So as a workaround people are using a companion client called room-assistant that was made to work with the mqtt_room component but instead is used with mqtt device tracker.
I think I have everything figured out with mosquitto and room-assistant installed on my rpi3 running hassbian it’s just that I don’t know how to configure the local.json file for room-assistant. All the documentation is for configure it with the mqtt_room component so how do I set it up for mqtt device tracker?
If someone who have this setup could post their local.json I would very much appreciate it!