Tunnel HTTP traffic from an EC2 instance to an Heroku Application

Tunnel HTTP traffic from an EC2 instance to an Heroku Application

We have a web application that runs perfectly on Heroku. However, that
application is not available from within a given subnetwork due to
firewall restriction on the Heroku IPs.
So built a simple EC2 instance with an elastic IP that works within the
firewall restriction. But rather than setting up a new application to run
on that instance I was thinking that we could setup some sort of HTTP
tunnel on port 80 (and maybe HTTPS as well) to direct the traffic directly
to the Heroku application that way we don't need to maintain a second
application.
Is there any way to achieve this ?