Booting from DVD

I have need to pass the host optical drive through to a guest and have the guest boot from it. I can set the boot order and make sure the ROM BAR is enabled, but the VM won’t boot from the dvd unless I explicitly select it in the boot menu (3rd option). I’d like to do this to avoid a lengthy and unnecessary dd copy to an ISO. That would essentially double my system installation time by reading the DVD twice.