Some scripts exist already for debian :
* https://wiki.debian.org/nfs4-kerberos-ldap
* https://wiki.debian.org/nfs4-kerberos-ldap-client
* https://vandervlis.nl/krb5/
So I made some modifications for a Devuan 2 Ascii server and Linux Mint 18.3 clients.
The scripts are not perfect but you can easily read and customize them.
The updated scripts : https://github.com/szutt/nfsv4-kerberos-ldap
My blog : https://szutt.github.io/en/