Given a resource limited setup consisting of 2 host machines (HyperV-01 and HyperV-02), is it OK to put the domain controllers in parent partition, instead of their own VM?

The main reason is that if the DCs go into a child partition, starting from cold on both machines could lead to a bit of an issue, as there'd be no DCs around until well after both parents have booted. I'm guessing this might cause undesirable effects.

Am I correct to be worried about joining the host systems to a domain that's only on VMs?

The biggest drawback I've heard so far is that if AD gets heavily used, its resources could cut into HyperV's. I'm not concerned about that for this deployment.

Any other suggestions? (Besides finding a 3rd machine and running AD on it.)