Best way to configure nixos LXCs on Proxmox

I’m trying to deploy nixos LXCs (generated with nixos-generate -f lxc -c lxc_cfg.nix) on proxmox. Proxmox allows you to configure an LXC’s IP, GW, DNS, hostname, root password and root SSH keys through the web interface. On other distro LXC templates, it does this by modifying different config files in /etc. The NixOS LXC template however doesn’t have /etc when proxmox extracts it for creating the container.

As of now, I’m able to make proxmox detect whether an LXC template belongs to nixos, and make it write the network/user configurations to different files. What is the best place and format to write these configs? What is the best way to make nixos pick up these configs? The easiest way to do this would be to write a shell script that reads these configs and applies them to the system, and run that as a oneshot systemd service on boot, but that feels hacky.