In the meantime I installed the custom cables and it was much easier to assemble. In the first attempt with a flipped layout (flipped core + flipped PSU) I had difficulties to mount the lower O2 panel, because the many cables always put pressure on the panel and it did not hold. Therefore, this time I have installed the PSU normally. It all fits, but the CPU temperature and fan noise was much better with the flipped PSU. Accordingly, I can only recommend this to everyone! My cables are now so short that I have to make new ones to flip it again.
Regarding the question of how to accommodate two 2.5" SSD in the front: I mounted them offset and only the outer one screwed to the case. That sits super tight so and the power cable I also created accordingly offset.
Here are a few pictures of the setup. There you can also see the SSD solution in detail.
Regarding the question of how to accommodate two 2.5" SSD in the front: I mounted them offset and only the outer one screwed to the case. That sits super tight so and the power cable I also created accordingly offset.
Here are a few pictures of the setup. There you can also see the SSD solution in detail.