A standalone host with only the local storage in a separate location and no clustering... I would leave that host out of the oVirt setup, and keep it under simple libvirt control. Then it's a simple matter of setting the VM up using libvirt and running virsh autostart VMNAME to make sure it restarts on reboot.
The engine manages the VMs, if it can't, then you can either do a dirty hack to bypass the engine and create a splitbrain between what the engine knows and what happens on the host, or ensure stable communication between the host and engine.