Mapping Active Directory Posix Attributes

I am in the process of attempting to migrate our authentication scheme from 389-ds to our existing Windows 2012 AD.

realm join [domain] -U [admin]

I am able to set up authentication with the SID+UID algorithm, but when i set the ldap_id_mapping= False to try and pull the manually configured posix attributes from AD it does not find any users.
[Initially SSSD fails to restart, i delete /var/lib/sss/db/* and restart sssd]

I have been having a hard time finding any solution that does not involve expensive 3rd party software, or even much documentation on the subject.

The reason for custom UID/GID is to enable users to continue using the existing Linux share without having to re-permission the entire NFS and other existing host files.

Any ideas or helpful docs would be greatly appreciated.

I cannot post configs as it is a disconnected network.