What is the best way to bootstrap CSR1000v? (ZTP or Day0)

Hi guys

I am struggling with ZTP with CSR1000v, this is not in a public cloud, it is a KVM/qemu deployment. configuring the router via DHCP option 6X or 150 is not consistent and I am looking for alternatives

One thing I am considering is injecting the startup config (a generic one that enables DHCP SSH and adds an user name) in the qcow2 image. Is there any other way to do it? (not sure if this will work as the image might be compressed somehow