configuring thruway to run on heroku

[tacman]

I have an application running on heroku, and I'd like to integrate Thruway, it's working locally, but not sure how to configure it to run remotely.

The Procfile simply runs a worker in a dyno:

web:  vendor/bin/heroku-php-nginx -C heroku-nginx.conf public/
worker: bin/console thruway:process:start -vvv

my configuration uses an environment variable to

voryx_thruway:
  realm: 'realm1'
  url: '%env(WAMP_SERVER)%' #The url that the clients will use to connect to the router
  router:
    ip: 127.0.0.1  # the ip that the router should start on
    port: 8080  # public facing port.  If authentication is enabled, this port will be protected
    trusted_port: 8081 # Bypasses all authentication.  Use this for trusted clients.
    authentication: false # true will load the AuthenticationManager
  user_provider: 'fos_user.user_provider.username'

the environment variable is set to the public port

WAMP_SERVER=ws://myapplication.herokuapp.com:8081

Heroku only allows one free dyno, so I couldn't run the router and worker independently. At one point, I thought there was a free public WAMP router (crossbar.io) that could be used for applications like this, where you didn't wan to run your own router, but perhaps I'm mistaken, as I can't find anything like that now.

Any suggestions on how to proceed?