Yes i did make some progress. I made a new PCB which now fits completely under the Rock5. I am able to boot from an NVME-ssd connected to two lanes while a JMB585 sata controller is connected to the other two lanes. I’m planning to use it as a NAS but i have only made some experiments, so i can’t say anything about reliability, especially since the power stage was designed for only one device.
You can have a look at the files here:
Files (altium.com)