Placement group on EC2 dedicated host

Hi, I know, as stated in the documentation, placement groups are not supported with EC2 dedicated hosts. But then, how to ensure two or more dedicated hosts will not run in the same rack ? For instance if you're building a cluster of whatever technology using bare metal hosts, you wan to ensure a rack failure will not bring it down. And Dedicated Instance is not an option if you want to be able to leverage, as much as possible, Microsoft BYOL.