From what I can tell, EasyEngine is unable to do what is required to allow Discourse to run on the same host: EasyEngine Community Forum. Since EasyEngine doesn’t do what it required, it makes it harder.
The simplest solution would be to run Discourse on a separate server on a subdomain, following the INSTALL-cloud instructions.
The way that I do it is to have CaddyServer do the reverse redirect; you might check Use Caddy instead of NGNIX as your reverse proxy.