The link to the video by LinusTechTips for anyone interested[0]. He actually had a heck of a time getting it working fully with all 7 graphics cards, as shutting a VM down wouldn't correctly release the card's resources (apparently an AMD-specific issue, but they denied it[1]), causing him to have to do a full reboot of the whole system every time one VM needed a restart[1].

[0] - https://www.youtube.com/watch?v=LXOaCkbt4lI (14:57)

[1] - https://www.youtube.com/watch?v=lThX7UovKCc (1:35:15 - really long stream of him disassembling it live, so forgive me for not finding exactly where he said each thing).