This is a great perl script that makes for an easy AuthorizedKeysCommand [1]. SSH with LDAP is definitely an easier way to distribute keys and manage permissions than logging into each box. It's also a single point of failure in a way, but you can at least keep it completely inside a private network, and LDAP is well-known and easy to secure.

1. https://github.com/AndriiGrytsenko/openssh-ldap-publickey