Well if you go with one of the open racks, just account for the cooling and don’t bunch everything together like in the post. Cramming things end to end without active cooling involved is just asking for them to take thermal damage. If each individual item you put in has directional cooling (ingress/egress), identify where they are, and make space. Just getting a cheap slot cooler to put at the top of bottom of one of the open racks would probably be fairly okay as long as there is airflow to each device.