Single-dyno setup on Heroku for Rails with both WebSocket and worker queue

Question

At the moment I have a small web application running on Heroku with a single dyno. This dyno runs a Rails app on Unicorn with a single worker queue.

config/unicorn.rb:

worker_processes 1
timeout 180

@resque_pid = nil

before_fork do |server, worker|
  @resque_pid ||= spawn("bundle exec rake jobs:work")
end

I would like to add WebSockets functionality, but from what I have read Unicorn is not one of the web servers that supports faye-websocket. There is the Rainbows! web server that is based on Unicorn, but I'm unclear if it's possible for me to switch and keep my spawn for the queue worker.

I suppose having more than a single dyno one could just add another dyno to run a Rainbows! web server for the WebSockets part, right? This is unfortunately not an option at the moment. Is there a way to get it working with a single dyno for my setup?

If not, what other options are available to get information from server to client e.g. based on asynchronous work being completed? I'm using poll for other things in the application, i.e. to start an asynchronous job that is handled by the worker process and upon completion the polling client (browser) will see a completion flag. This works, but I'd like to improve it if possible.

I'm open to hear about your experiences and suggestions. Thanks in advance!