I realized that the cable routung for all the cables i need is pretty straightforward, as my mainboard has a rater unusual layout: 
I marked all the ports i am planning to use (at some point) red, and i will be able to reach all of them without the need for extra cutouts. i can just rout the cables from the motherboard around the mobo tray and out of sight, and then where they need to go to. I have 12mm space behind there, so that's no problem at all.
I added that many cubes for rigidity and mainly consistency of the asthetics, so that now there are the same amount of cubes front to back and top to bottom, but i get what you're saying. I'll try how it looks later.
I tried your suggestion but didn't really like the look that much. And as i said before, I have 12mm of space behind the motherboard so that won't be too big of a problem. I'm only using one ssd anyways, and just recently upgraded to it, and even a second one would be no problem.
I'll try and contact some in the next days, thanks for the tip!
