[Catalyst] Proxy setup: frontend port from c.uri_for

I've setup multiple instances of the same application as follows:

Host system: Apache shared hosting
inst1.example.com:80
inst2.example.com:80 -> IP-addr:1180 (proxy)

Chroot system: Apache backend
IP-addr:1180

I want c.uri_for, c.request.base and c.uri_with to return the frontend
port 80. I've set the following headers:

X-Forwarded-Host: inst2.example.com:80
X-Forwarded-For: IP-addr

Still, I am unable to get the frontend port. I even set the
using_frontend_proxy config variable to 1. What am I missing?