It offends my sense of Deutsche Ordnung to do that sort of thing on more than a temporary basis.
I took a long time building the signature Skylake (and need to update that sig, too.) It resulted in a very fine-tuned combination of air-flows. There is, for instance, a square/rectangular array of 1cm-dia holes in the motherboard pane directly underneath and surrounding the rear of the processor socket. Air is drawn across the motherboard from both these 1cm holes and from the rear edge of the visible left side or top of the motherboard together with the I/O plate. It is pulled from both input sources by a single barrel-fan -- 12" long. The mobo is recessed from the case right side-panel by maybe 2+cm -- I'd have to measure it. But there is plenty of room there for mounting SSDs affording cabling convenience according to my cable-dressing-plan. And you could mount those SSDs so as not to interfere with the custom filter I designed for those mobo-pan holes. Everything is designed to assure that you don't have to remove something else before removing a component, although I do have to remove a fan-filter to get at the conventional forward drive cages, and disconnect the PWM plugs.
Still -- "C'mon, now." Unless you are really building a compact rig, or unless you have every SATA port connected to an internal drive, why should you really need anything more than conventional mountings? The dual-SSD/2.5"-HDD bracket that fits probably all cases on the market costs maybe $10, and I keep spares, because it saves trouble to have them. I keep track of the appropriate screws.
I'm about finished building a system with 4TB of storage, split across three disks, between two Oses. I would get by with two, but one disk must be shared by OSes in operation one at a time, and the others include volumes that must be separated. I'll be lucky if I ever fill half of it, or when I do, I'll be looking at newer models. I consider three drives as a modest luxury. But in this case, it's a viable combination that I shouldn't ever need to change much. I mean -- how many storage devices should you need, and for what? It would vary -- if only because I store a lot of files on a home server, and other people may only use a single desktop and would never think of dropping a CAT6 cable from their attic bedroom to the ground floor. Some people buy a lot of mobile external backup disks or devices. I use them sparingly. So it all depends.