I use Ansible playbooks to provision VMs and LXC containers on Proxmox.
The playbooks add the new hosts automatically to FreeIPA, set up SSH, etc. See:
-https://github.com/alexpdp7/ansible-create-proxmox-vm-ubuntu1604-ipa
+https://github.com/alexpdp7/ansible-create-proxmox-host
https://github.com/alexpdp7/ansible-create-proxmox-centos7-ipa
I also use Ansible for some orchestration tasks (such as deploying FreeIPA replicas, handling Letsencrypt certificates, etc.).