The container files are under /var/lib/machines/nsdc so you may just use the editor of your host system.
With following commands you create a custom template for the containers smb.conf.include:
mkdir -p /etc/e-smith/templates-custom/var/lib/machines/nsdc/etc/samba/smb.conf.include
echo "# accept join from FreeNAS" > /etc/e-smith/templates-custom/var/lib/machines/nsdc/etc/samba/smb.conf.include/20auth
echo "ldap server require strong auth = no" >> /etc/e-smith/templates-custom/var/lib/machines/nsdc/etc/samba/smb.conf.include/20auth
expand-template /var/lib/machines/nsdc/etc/samba/smb.conf.include
I asked some of our freenas users: