Best way to move from a (very old) proxy server

We are running Red Hat Proxy server 5.3 release on a very old RHEL (4.9).
Despite this obsolete configuration, our server is still working with a very simple scenario, having to manage updates for about 20 registered systems.
We are planning to upgrade both the o.s. and proxy, which have reached long ago their end of life, migrating from physical to virtual infrastructure.
We're trying to figure out what is the best way to keep our scenario as simple as possible, avoiding for example to carry out an entire Satellite installation.
Is there a modern equivalent of Red Hat Proxy that interfaces with the RedHat servers, featuring (only) basic caching?