I stumbled upon this thread. It learns me that the ISA CF adapter will not work with the Sidecar because of conflicts in the BIOS. This can be solved, but I don't have the skills nor knowledge to perform this.
So this is the outcome at this time of the ISA CF adapter adventure.
I tried the Western Digital Filecard and it worked a few times. After that the Amiga partition vanished. So it's not reliable anymore.
I digged up the A1060 sidecar and connected it to my spare A1000. While it booted fine, it did not recognize the floppy diskdrive. So I thougt I format and prepare a harddisk, connect it to the ISA CD adapter, and hope the Sidecar would boot from it. It didn't. It repeats bleeping when the floppy diskdrive is needed, the drive's light blinks for two seconds and it starts over to check the RAM. And over and over again.
I now believe the floppy disk drive is faulty. As I have no spare I need to get one.
To be continued.