Fedora handles this use case beautifully with MirrorManager, which includes the EPEL repos as well. All of the logic is server side, when a yum/dnf client connects to the Metalink server to fetch a mirror list from our IP block it gets sent our internal mirror - I wish more distros had similar setups.
Yes, the mirror is configured as private and is only served to machines in my IP range - since it’s on the internal network it does nobody else good to have access.