Currently the generated puppetmaster and puppet_ca_server hostnames are the same as the smart proxy.

This isn't always the case. When you have a setup:

Foreman <-> Smart Proxy <-> Hosts

Here you have a private LAN between Foreman and its Smart Proxies. There is another network which has hosts. Here you'd have the Puppet (CA) on the host network. In hostnames:

• foreman.lan.example.com (192.0.2.2)
• proxy.lan.example.com (192.0.2.3)
• proxy.wan.example.com (198.51.100.3)
• puppet.wan.example.com (198.51.100.4)
• puppetca.wan.example.com (198.51.100.5)

In /etc/foreman-proxy/settings.d/puppet_proxy_puppet_api.yml you'd configure:

:puppet_url: https://puppet.wan.example.com:8140

In /etc/foreman-proxy/settings.d/puppetca_http_api.yml (Proxy 1.22) you'd configure:

:puppet_url: https://puppetca.wan.example.com:8140

By using the new capabilities framework we can expose these settings to Foreman. Foreman can use these to present the correct hostnames, like in the provisioning templates.