1. don't use any proxy features for provisioning (no dns/dhcp/tftp)
2. use image-based provisioning without cloud-init (the ssh based)
3. try to create a host (I've tested with libvirt)

The host gets created even when no IP address specified.

I've tested this with libvirt, but I guess the issue is the same
with all providers that don't provide the IP address via the API.